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KLE6 1 RIQ>  JjJ^H 


THE  KLAWITERS 

1  61  56  A  lei  ma  Avenue 

'acific  Palisades,  California 


Making  knot. 


The  knot  made. 


Connecting  socket.     Spare  wire  end  to  be  cut  off. 
PLATE  I. 


WIRING    HOUSES 


FOR   THE 


ELECTRIC  LIGHT 


TOGETHER     WITH 


SPECIAL  REFERENCES  TO  L(  )\V  VOLTAGE 
BATTERY  SYSTEMS 


BY 


NORMAN  H.  SCHNEIDER 

Author  of  Electrical  Instruments  and  Testing:  Management 

of  Electric  Power  Plants;  Induction  Coils 

and   Coil   Making;    &c,   &c. 


SECOND   EDITION    REVISED    AND   ENLARGED 


NEW    YORK  : 

SPON  &  CHAMBERLAIN,  123  LIBERTY  ST. 

LONDON  : 

E.  &  F.  X.   SPOX,   Ltd,  57   HAYMARKET,   S.  W. 

1916 


(No.  33) 


Copyright,    1911, 
By    Spon   &   Chamberlain-. 

Copyright,    1916, 
By   Spon   &  Chamberlain. 

ALL     RIGHTS    OF    FOREIGN    TRANSLATIONS    ARE    RESERVED 


Tress    of    Barr    &    Hay  field,    12    Dutch    Street,    New    York,    U.    S.    A. 


SRLF 

URL 


PREFACE    TO    SECOND    EDITION 


A  supply  of  electric  current  in  the  house  for  light- 
ing, cooking,  and  for  the  operation  of  the  labor- 
saving  household  appliances  is  no  longer  looked  on 
as  a  luxury. 

Electricity  in  the  house  is  a  necessity. 

The  wiring  of  the  house  therefore  is  a  subject 
awakening  vast  interest  and  the  second  edition  of 
this  book  has  become  necessary  in  order  to  keep 
abreast  of  the  constantly  arriving  improvements  in 
electrical  work. 

Although  many  farms  and  isolated  dwellings  are 
installing  low  voltage  plants  of  their  own,  operated 
by  a  gasoline  engine,  there  exists  no  reason  why 
the  wiring  itself  should  not  be  as  safe  as  that  re- 
quired for  the  higher  voltage  of  the  Public  Service 
lines.  Therefore,  the  directions  in  the  succeeding 
pages  are  devoted  to  first  class  work  only,  and  that 
suitable  for  all  ordinary  household  voltages. 

The  rules  of  the  National  Board  of  Fire  Under- 
writers have  been  freely  consulted,  an  extensive 
digest  with  notes  is  given  in  a  complete  chapter  of 
this  edition. 

In  addition  to  practically  all  the  information  con- 
tained in  the  former  edition,  there  has  been  added 
thirty-two  new  pages  on  conduit  wiring  and  con- 
centric wiring  and  a  number  of  full-page  plates. 

Condulets  and  other  fittings  for  conduit  work 
have  been  described,  together  with  BX  armored 
cable  and  the  handling  of  it. 

•  •  • 

111 


IV  PREFACE 

Concentric  wiring,  a  system  of  wiring  much  used 
abroad  is  treated  on,  several  illustrations  of  the  wire 
and  the  new  line  of  fittings  being  developed  by  the 
General  Electric  Company  being  shown  through  the 
courtesy  of  the  latter  company. 

There  exists  some  opposition  in  the  United  States 
to  this  concentric  wiring  due  solely  to  the  fact  that 
it  is  supposed  to  be  a  rival  of  the  present  systems, 
and  its  adoption  to  entail  great  losses  to  invest- 
ments in  tools  and  machinery  devoted  to  the  manu- 
facture of  the  ordinary  fittings.    This  is  not  logical. 

Concentric  wiring  is  an  addition  to  the  modern 
methods  and  has  its  field  in  the  less  pretentious 
dwellings.  It  is  not  likely  to  supplant  any  other 
form  of  wiring  to  any  extent  for  years  to  come 
other  than  small  circuits  in  open  work  or  moulding. 

It  does,  however,  present  a  new  additional  line 
of  convenient  fittings  to  be  likened  to  the  condulet 
and  BX  lines. 

The  author  wishes  to  thank  the  following  for 
illustrations  or  information  : 

The  Bryant  Electric  Mfg.  Company  and  The  H. 
T.  Paiste  Company  for  electric  fittings.  The 
Sprague  Electric  for  illustrations  of  BX  armored 
wire  and  multilets,  the  Crouse  Hinds  Company  for 
illustrations  of  condulets,  the  Western  Electric 
Company  for  illustrations  from  their  book  "Bright- 
ening up  the  Farm,"  and  to  the  General  Electric 
Company  for  illustrations  and  information  on  their 
new  line  of  concentric  wiring  appliances. 

Also  he  expresses  his  appreciation  to  Mr.  R.  S. 
Hale  for  information  on  concentric  wiring,  to  Mr. 
John  Deegan  for  reading  manuscript  and  to  Mr. 
Alfonso  Ciani  for  the  excellent  photographs. 

Norman  H.  Schneider. 
Jersey  City,  N.  J. 


CONTENTS 


CHAPTER  I. 

Introduction. 

Lamp  ho>cfers.     The  circuit  defined. 


CHAPTER  II. 

Planning  the  Wiring. 

The  plan  to  be  followed.  Material  needed.  Laying 
out  the  work.  Centering  ceiling  outlets.  Marking 
outlets  with  the  bit.  Wiring  plans.  Pockets. 
Boring  and  tubing.  Running  the  wires.  Knobs 
and  their  use.  Wire.  Making  fast  to  the  knobs. 
Joints.  Splicing,  soldering  and  taping.  Ceiling 
boards.     Finishing  wiring 7 

CHAPTER  IIL 

Completing  the  Installation 

The  service  switch  and  its  installation.  Switch  box. 
Cut-outs.     Iron  box  and  fused  switch 37 

CHAPTER  IV. 

Installing  the  Lights. 

The  outlet  wires.  Installing  the  light*.  Rosettes. 
Making  up  drop  lights.  Fixtures.  Wiring  single 
pole  switches.  Hall  lights.  Wiring  three  way 
switch 46 


VI  CONTENTS 

CHAPTER   V. 

Other  Methods  of  Wiring. 

Open  or  cleat  work.  Wiring  in  wooden  moulding. 
Moulding  taps  and  cross  overs.  The  wall  moulding 
method.  Outdoor  service.  Bringing  in  the  service 
through    iron   pipe 60 

CHAPTER  VI. 

Materials  and  Notes. 

Estimating  the  material  required.  Loom,  knobs, 
split  knobs,  screws  and  nails.  Mouldings.  Bits. 
Tapes.  Table  of  copper  wire.  Figuring  the  size 
of   wire    required 75 

CHAPTER   VII. 

Conduit  and  Protected  Wiring. 

Conduit  work  safer.  Armored  cables.  Installing 
armored  cables.     Pipe  conduit.     Concentric  wiring..     84 

CHAPTER  VIII. 

Underwriters  Rules  and  Notes. 

The  National  Code.  General  suggestions.  Inside 
work.     Wires.     Appliances.     Conduit  work 100 


LIST  OF   ILLUSTRATIONS 


FIG.  PAGE 

1  Weatherproof  s.  icket 

2  Brass  socket 3 

3  Floor  showing  joists 1 1 

4  Plan  of  house  circuits 12 

5  Plan          "             "      14 

6  Plan          "             "      16 

7  Plan          "             "      16 

S  Cutting  floor  board 17 

9  Raising  floor  board 18 

10  Floor  showing  tubing  and  wiring 20 

11  View  of  pockets  and  wiring 23 

12  Hitching  wire  to  knob 25 

13  Tying  wire  to  knob 25 

14  Protecting  crossing  circuit 27 

15  Method  of  splicing 28 

16  Making  a  tap 29 

17  Placing  ceiling  boards 33 

18  Main  cut-out 40 

19  Cut-out  box  with  wires  at  top  and  bottom 41 

20  Cut-out  box  with  wires  at  top 4- 

21  D.  P.  vS.  T.  Knife  switch.      Fused 43 

22  D.  P.  Panel  switch 43 

23  Cut-out  box  for  2  circuits 44 

24  Iron  box  and  service  switch 45 

25  Wiring  an  outlet 46 

26  Rosette  for  concealed  work 48 

27  Moulding  rosette 48 

28  Cleat  work  rosette 49 

29  Unfused  rosatte 49 

vii 


Vlll  LIST    OF    ILLUSTRATIONS 

FIG.  PAGE 

30  Making  up  drop  light 50 

31  Fixture,   two   lights 52 

32  Wiring  a  switch 54 

33  Single    pole    switch 55 

34  Wiring  single  pole  switch 56 

35  Wiring  three   way   switch 58 

36  Turning  corner.     Cleat   work 61 

37  Paiste     taplet 64 

38  Paiste    cross-over 65 

39  Plan   for  wall  moulding  system 67 

40  Wiring  switch   for  wall  moulding 68 

41  Iron  pipe   for  service 71 

43  Service   from  pole 73 

43  Tie  and  insulator 74 

44  Insulator    and    iron,  bracket 74 

45  How   to   cut   armored   cable 89 


LIST  OF  PLATES.  face 

PAGE 

Plate        L— Making  up  a  Socket Frontispiece 

Plate        II. — Receptacle   and    switch 3 

Plate      III. — Making  splices   and   taps 38 

Plate      IV. — Making  up  a  drop  light 50 

Plate        V.— Sprague  BX  and  fittings 87 

Plate     VI. — Some   typical   Condulets 91 

Plate    VII. — General    Electric    Concentric    wiring    ap- 
pliances    95 

Plate  VIII. — General    Electric    Concentric    wiring    ap- 
pliances    97 

Plate      IX.— Example  of  pipe  conduit  wiring '. .  99 


CHAPTER  I. 


Introduction. 

Before  light  can  be  obtained  from  the  in- 
candescent lamp  it  must  be  placed  in  a  suitable 
receptacle  or  socket  and  connected  to  wires  leading 
from  the  battery. 

The  socket  consists  of  a  shell  having  insulated 
contacts  of  brass,  into  which  the  lamp  screws  and 
makes  connection  between  its  base  and  the  con- 
tacts in  the  socket. 

The  wires  having  been  attached  to  this  socket 
convey  the  current  through  these  contacts  to  the 
filament  in  the  lamp  and  the  filament  becomes  white 
hot,  giving  the  desired  illumination. 

It  is  of  vital  importance  that  the  wires  carrying 
current  shall  not  touch  each  other  when  bared 
or  the  current  will  flow  through  such  point  of 
contact  and  cause  a  short  circuit  which  is  a  sudden 
rush  of  uncontrolled  current. 

Such  a  short  circuit  would  very  likely  have  dis- 
astrous results  if  not  guarded  against.  This  is 
done  by  covering  the  wires  with  a  covering  or  in- 
sulation which  prevents  the  passage  of  electricity. 
All  metal  parts  which  are  to  carry  current  are  also 
insulated  either  by  hard  rubber,  porcelain  or  by 

ae  other  suitable  means. 


WIRING    HOUSES 


One  of  the  simplest  sockets  to  hold  the  lamp  is 
shown  in  Fig.  1  having  two  short  wires  protruding 
from  the  upper  part  which  are  to  be  spliced  or 
tapped  on  to  the  main  wires  of  the  circuit.  The 
socket  being  of  porcelain  is  especially  adapted  for 
use  outdoors  or  in  damp  places.  The  wires  may 
be  of  any  length  desired  if  specially  ordered  but 
usually  they  are  a  few  inches  in  length.  The 
copper  wire  is  stranded  giving  greater  flexibility 
and  less  likelihood  of  breaking  off  when  the  socket 
is  swayed  by  the  wind. 


Fig.  1. 

In  attaching  to  the  circuit  wires,  the  socket  wires 
are  to  be  bared  of  insulation  for  about  three  inches, 
scraped  bright  and  twisted  on.  A  good  plan  is  to 
divide  the  strands  in  each  wire  into  two  parts, 
bending  them  at  right  angles  so  as  to  form  the  letter 
T.  The»  each  half  is  twisted  around  the  circuit 
wire  separately  in  opposite  directions  which 
ensures  a  good  support  for  the  socket  and  less 
liability  of  breaking  at  the  point  of  connection. 


Receptacle 
for  lamp 
directly  con- 
nected to 
circuit. 


The  same  receptacle  for 
lamp  controlled  by  a 
single   pole   snap    switc-h. 

Note  loom  protection 
where  wire  crosses — a 
tube  also  may  be  used 
and  is  preferable  where 
two  opposite  circuits 
cross. 


PLATE  II. 


INTRODUCTION  3 

As  stated  elsewhere  all  such  connections  should  be 
well  soldered  and  taped. 

Such  an  arrangement  of  a  weatherproof  socket 
tapped  on  to  a  wire  is  of  use  in  its  place,  that  is  in 
damp  locations,  but  for  a  dwelling  house  where 
something  more  convenient  and  ornamental  is 
desired  brass  sockets  are  used  as  illustrated  in 
Fig.  2.  These  having  no  permanent  wires  for 
ready  connection  like  the  weatherproof  socket  must 
be  attached  by  means  of  other  pieces  of  wire,  or 
by  flexible  incandescent  lamp  cord. 


Fig.  2. 

These  brass  sockets  are  provided  with  a  key  pro- 
truding from  the  side  by  means  of  which  the  current 
may  be  turned  on  or  off  as  desired  thus  controlling 
the  light.  The  key  operates  a  switch  in  the  socket, 
which  switch  is  a  device  consisting  of  fixed  and  of 
movable  contacts  through  which  the  current  passes 
when  the  switch  is  turned  on.  Turning  off  the 
switch  or  key  separates  these  contacts  and  the 
current  can  no  longer  pass  until  the  key  is  again 
turned. 


4  WIRING    HOUSES 

Switches  are  also  made  in  a  great  variety  for  lo- 
cation in  cases  where  it  is  desired  to  turn  on  or  off 
the  lights  without  reaching  up  to  the  socket.  And 
sockets  are  made  as  in  the  weatherproof  socket 
without  keys  or  switches  contained  in  them. 

A  combination  of  wires  and  lamps  with  their 
accessories  is  known  as  a  circuit. 

Circuits.  The  simplest  practical  circuit  would 
consist  of  a  pair  of  insulated  wires  leading  from  the 
battery  to  a  key  socket  holding  the  lamp.  The 
key  of  the  socket  being  turned  would  either  light 
or  extinguish  the  lamp.  The  essential  parts  then 
of  a  circuit  are  the  wires  to  carry  the  current,  the 
socket  or  holder  for  the  lamp  and  the  switch  or  key 
to  control  the  light.  The  wires  would  be  insulated, 
that  is,  covered  with  some  substance  which  is  not 
a  conductor  of  electricity  to  prevent  a  contact  of 
the  metallic  portion  of  the  wires  and  thereby  a 
"  short  circuit." 

In  a  simple  circuit  a  few  feet  long  the  insulation 
on  the  wires  would  be  deemed  sufficient  to  protect 
the  wires  but  where  the  wires  are  to  be  extended  for 
a  distance  they  would  have  to  be  supported  on 
insulated  supports. 

The  latter  are  of  glass  or  porcelain,  being  gen- 
erally called  insulators,  except  the  porcelain  ones, 
to  which  the  common  name  of  "  knobs  "  is  usually 
given. 

Other  control  of  the  light  than  by  means  of  the 
key  in  the  socket  would  probably  be  unnecessary. 


INTRODUCTION  5 

Going  a  step  farther  a  fuse  would  be  added  to 
prevent  the  copper  wire  becoming  dangerously  hot 
should  an  accidental  short  circuit  or  metallic  con  - 
tact  be  made.  This  fuse  would  be  a  piece  of  special 
lead  alloy  wire  and  would  melt,  opening  the  circuit 
when  the  current  became  too  strong.  Lead  alloys 
are  used  because  they  melt  at  a  lower  temperature 
than  copper  without  becoming  hot  enough  to  do 
damage  before  melting.  Aluminum  wire  is  also 
employed  for  fuses  but  principally  in  the  high 
ranges  of  current.  Other  forms  of  fuses  will  be 
treated  of  in  their  place. 

Then  another  light  might  be  added  or  perhaps 
two  by  means  of  wires  leading  from  the  main  wires. 
These  circuits  extending  for  considerable  distances 
and  being  most  probably  permanent  would  be  on 
insulators  or  otherwise  safely  supported. 

The  next  improvement  would  be  switches  to 
control  the  lights  and  a  main  switch  to  cut  off  the 
battery  fTom  all  connection  with  the  wires.  The 
main  swicch  and  the  porcelain  fuse  block  should  be 
enclosed  in  an  iron  box  or  a  wooden  one  lined  with 
asbestos. 

Elaborations  will  of  course  suggest  themselves 
such  as  the  installation  of  more  lights,  special 
means  of  control,  fixtures  and  methods  of  running 
the  wires  to  meet  special  requirements. 

It  is  assumed  that  a  house  is  ready  for  wiring  and 
the  details  of  the  number,  location  and  size  of  the 
lights  have  been  decided  upon. 

While  the  scope  of  these  pages  is  more  particu- 


WIRING    HOUSES 


larly  directed  to  the  wiring  for  low  voltage  lighting 
from  storage  batteries,  the  methods  described  will 
be  suitable  for  regular  110  volt  installations.  In 
the  latter  case  the  local  rules  affecting  wiring  should 
be  consulted,  and  if  insurance  is  to  be  carried,  the 
insurance  rules  should  be  consulted.  It  is  im- 
possible to  give  in  a  book  all  the  rules  which  are 
often  different  in  each  State  and  town.  So  far  as 
possible  all  general  rulings  have  been  consulted  in 
preparing  these  directions  and  the  methods  to  be 
described  are  safe. 


CHAPTER  II. 


Wiring  A  House. 

Before  starting  to  wire  a  house  the  plan  or  specifi- 
cations should  be  decided  upon  showing  the  num- 
ber and  wattage  of  the  lamps  and  the  location  of 
the  lamp  outlets.  (It  is  customary  to  use  the  term 
outlet  instead  of  lamp,  as  for,  example,  a  house 
would  be  wired  for  ten  outlets,  not  for  ten  lights) . 

The  location  of  the  switches  should  also  be  set- 
tled as  well  as  the  point  of  entrance  for  the  service, 
that  is  where  the  wires  from  the  electric  light  mains 
or  battery  shall  come  in. 

If  a  small  private  plant  it  may  be  located  in  the 
cellar  in  which  case  the  main  switch  or  service 
switch  will  be  in  the  cellar.  But  if  the  plant  is 
located  in  an  outhouse,  then  the  wires  must  come 
in  the  same  as  those  from  an  electric  light  company 
in  most  cases  leading  to  insulators  fastened  to  the 
walls  at  a  height  from  the  ground  but  may  lead 
from  there  into  the  cellar  if  desired. 

The  exact  location  should  be  settled  before  wiring 
as  all  wires  to  the  lighting  circuits  in  the  house 
must  run  to  the  service  or  main  switch  so  that  they 
may  be  more  conveniently  controlled. 

Material  Required.     It  will  be  better  to  read 

7 


8  WIRING    HOUSES 

generally  through  the  directions  for  wiring  given 
here  and  then  survey  the  job  before  attempting  to 
figure  out  what  material  is  required  if  the  operator 
is  inexpert.  For  this  reason  much  of  the  de- 
scription of  material  has  been  left  to  a  later  chapter 
and  described  separately.  It  then  becomes  a 
simple  matter  to  measure  with  a  rule  the  amount 
of  wire  wanted  and  the  other  supplies  will  be  in 
proportion.  Of  course  such  things  as  sockets  and 
switches  depend  upon  the  actual  lighting  require- 
ments. 

Laying  Out  the  Job.  Suppose  it  is  desired  to 
conceal  the  wiring  in  a  finished  frame  house.  The 
first  thing  is  to  lay  out  the  outlets  or  points  where 
the  lights  are  to  go  and  mark  the  walls  or  ceiling 
with  a  pencil  cross  at  the  spot,  also  marking  in  the 
loeation  of  switches  if  any. 

Where  outlets  are  required  in  the  centre  of  a  room 
the  ceiling  must  be  marked  at  the  centre  spot. 
This  may  be  done  in  two  ways.  The  width  of  the 
floor  is  first  measured  and  the  result  divided  in 
half,  a  long  line  than  being  penciled  on  the  floor 
at  this  point,  or  a  stick  laid  down  at  right  angles  to 
the  width  of  the  room.  The  length  of  the  room  is 
then  measured  and  likewise  halved,  the  place 
where  the  half  length  and  the  half  width  meet  is 
the  centre  of  the  room.  The  center  of  the  ceiling 
may  be  readily  found  by  means  of  a  plumb  bob 
or  a  weight  on  a  string  held  to  the  ceiling  and  shifted 
until  the  plumb  bob  hangs  directly  over  the  mark. 


WIRING   A    HOUSE  9 

Where  the  string  touches  the  ceiling  marks  the 
center. 

Another  and  quicker  method  usually  followed 
by  the  regular  wireman  is  to  procure  a  stick  about 
half  the  width  of  the  room  in  length  and  standing  on 
a  chair  or  step  ladder  shove  one  end  of  the  stick 
against  the  wall  near  the  ceiling  and  mark  on  the 
ceiling  where  the  other  end  reaches.  Then  put  it 
against  the  other  side  of  the  room  near  the  ceiling 
and  mark  again  in  like  manner.  This  is  done  four 
times  when  the  four  marks  on  the  ceiling  being 
all  of  equal  distance  from  the  walls  can  be  used  to 
get  the  exact  centre  by  means  of  a  foot  rule. 

The  stick  must  be  held  straight  each  time  parallel 
to  the  wall  or  the  measurement  will  be  off.  Where 
rooms  are  of  irregular  shape  the  centre  or  location 
for  the  ceiling  outlet  may  be  decided  arbitrarily. 
In  the  case  of  a  bay  window,  the  latter  is  not  to  be 
taken  as  included  in  the  dimensions  of  the  room, 
but  is  to  be  ignored. 

A  long  thin  bit  about  one  quarter  of  an  inch  in 
diameter  and  say  eighteen  inches  long  is  fastened 
in  a  brace  and  carefully  driven  up  through  the  mark 
on  the  ceiling  until  it  comes  through  the  flooring  of 
the  upstairs  room. 

The  little  hole  in  the  floor  will  show  whereto 
take  up  the  board  later  on.  It  is  very  rare  that  the 
center  of  a  floor  will  correspond  with  the  centre 
of  the  ceiling  right  below  it  as  the  upstairs  rooms 
are  often  laid  out  differently  than  those  down  stairs 
For  this  reason  it  would  be  very  hard  to  locate  the 


10  WIRING    HOUSES 

exact  spot  where  the  floor  board  should  be  removed 
or  the  pocket  cut  in  order  to  get  exactly  over  the 
ceiling  outlet,  unless  this  above  method  was  pur- 
sued. The  hole  bored  by  the  small  bit  is  hardly 
noticeable  in  the  flooring,  except  it  be  looked  for. 

Where  a  partition  comes  exactly  over  the  bored 
hole,  the  skirting  or  mop  board  must  be  removed. 
This  is  best  done  by  driving  in  the  nails  with  a  nail 
punch  and  then  lifting  off  the  mop  board.  If  it  is 
attempted  to  pry  it  off,  it  will  be  surely  split  and 
the  plaster  may  come  off  in  patches.  But  having 
driven  in  the  nails  there  is  nothing  holding  the 
board  in  place  but  the  edges  of  the  plaster  and  the 
fit  with  the  floor. 

Having  drilled  all  the  outlets  and  marked  where 
the  switches  are  to  go,  the  next  thing  is  to  figure  out 
the  easiest  and  shortest  route  for  the  wires.  This 
will  not  only  save  labor  and  mistakes  when  the 
work  is  under  way  but  will  enable  a  list  to  be  made 
of  the  material  needed. 

Taking  the  case  of  a  two  story  frame  dwelling 
house  with  the  service  or  battery  plant  in  the 
cellar,  the  outlets  on  the  first  floor  will  be  wired 
through  holes  or  "  pockets  "  cut  temporarily  in 
the  floor  above.  The  bed  rooms  may  probably 
be  wired  from  the  attic  which  if  not  floored  will 
facilitate  the  wiring  operations. 

In  the  first  place  look  which  way  the  floor  joists 
lie  and  arrange  to  have  as  many  of  the  circuits  as 
possible  run  in  the  same  direction  to  avoid  boring 
holes  transversely  through  the  joists. 


WIRING   A    HOUSE 


11 


This  is  well  illustrated  in  Fig.  3  which  represents 
a  portion  of  a  floor  with  part  of  the  boards  cut 
away.  The  joists  run  in  the  direction  of  arrow  B 
while  the  flooring  runs  like  arrow  A . 

If  the  circuit  is  to  run  in  the  direction  of  arrow  A , 
the  joists  must  be  bored  and  porcelain  insulating 


Fig.  3. 


tubes  inserted  in  the  holes  as  will  be  described  later. 
In  order  to  bore  the  holes  in  every  joist  the  entire 
board  or  two  boards  covering  the  route  must  be 
taken  up. 

But  where  the  wires  run  in  the  direction  of  arrow 
B  it  is  not  necessary  to  bore  any  joists  as  the  wires 
will  lie  between  them,  and  the  entire  board  need 


12 


WIRING    HOUSES 


not  be  taken  up  but  only  a  small  portion  as  will  be 
seen  later. 

Wiring  Plans.     In  the  following  four  plans  are 
shown  some  typical  arrangements  of  wiring.     The 


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Z2 


~m»- 


X- 
K 


X- 

H 


B 


CP-— SJ 


ZJ 


L_ 


Fig.  4. 


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T 

-XL 


-XM 


X  — 
G 


i 


/ 


-ell 


plans  are  those  of  the  first  floor  and  show  the  out- 
lets of  that  floor,  but  the  wiring  is  as  it  would  ap- 
pear when  viewed  from  the  second  floor  under 
which  it  is  located. 


WIRING   A    HOUSE  13 

In  order  not  to  complicate  these  plans  no  clothes 
closets,  bathrooms  or  the  usual  details  of  house 
construction  are  shown.  The  idea  is  merely  to 
show  in  a  brief  manner  the  direction  which  the 
wiring  would  take,  the  two  wires  being  indicated 
by  a  single  firm  line  or  dotted  line. 

The  arrows  indicate  the  direction  of  the  joists 
and  floor  boards,  arrow  A  pointing  in  the  direction 
of  the  floor  boards  and  arrow  B  in  the  direction 
of  the  joists. 

The  heavy  lines  show  where  it  is  necessary  to 
take  up  complete  boards  and  to  bore  and  tube  the 
joists.  The  dotted  lines  show  where  the  wires 
are  run  between  the  joists. 

It  is  thus  possible  to  see  at  a  glance  the  best 
path  for  the  wires. 

The  circle  C  is  at  the  place  where  the  wire  from 
the  service  or  main  switch  will  come  up  in  the  wall 
to  feed  the  circuit. 

Consider  first  Fig.  4.  The  flooring  will  be  taken 
up  between  points  E  and  F  in  the  manner  to  be 
■described  later. 

The  branch  wires  to  outlets  D,  K,  H  and  G 
will  be  joined  or  "  tapped  "  on  to  the  circuit 
between  E  and  F  and  the  wires  to  the  service  down 
the  wall  at  C  will  be  also  tapped  on.  This  ta'pping 
will  only  require  pockets  to  be  taken  up  at  in- 
tervals possibly  one  at  D,  K,  H  and  G,  and  one  or 
two  between  L  and  K  and  between  M  and  H. 
The  point  at  C  will  probably  be  opened  by  re- 
moving a  portion  of  the  mop  board  or  skirting. 


14 


WIRING    HOUSES 


In  Fig.  5  is  another  layout  of  the  same  job  where 
it  will  be  noticed  that  there  will  be  more  boards 
to  remove  and  more  boring  as  shown  by  the 
heavy  lines. 


f   \ 


^p--^ 


r 


c_ 


1 


-£ 


X 


m 


b 


eL 


Fig.  5. 


The  labor  is  greater  in  this  scheme  and  nothing  is 
gained  thereby. 

In  Fig.  6  is  a  plan  of  another  house  drawn  in  the 
same  manner  the  boards  running  like  arrow  A 


WIRING  A  HOUSE  15 

and  the  joists  like  arrow  B.  Here  the  boring 
through  the  joists  will  take  the  direction  of  heavy 
lines,  but  the  wires  may  be  continued  past  outlet  D 
and  down  in  the  wall  to  the  cellar. 

Outlets  E  and  F  and  G  will  require  branch  wires 
run  to  them. 

In  Fig.  7  is  another  house  plan  where  the  wires 
run  in  a  complete  circuit  from  outlet  F  to  outlet  D 
and  the  service  wires  tapped  on  at  C  where  they  go 
down  in  the  partition.  If  the  partition  is  not 
handy  the  main  wires  may  continue  to  the  point 
E  and  there  go  to  the  service. 

Each  house  presents  its  own  conditions  but  a 
little  study  will  disclose  the  best  and  most  handy 
route  for  the  wiring. 

As  the  simplest  of  these  circuits,  the  last  one  will 
be  considered  and  the  operations  more  particularly 
referred  thereto  although  most  of  the  directions 
given  will  be  general  in  application. 

Pockets.  The  first  operation  in  wiring  will  be  to 
open  pockets  at  intervals  in  the  floor  or  to  remove 
floor  boards  in  order  to  gain  access  to  the  space 
beneath. 

The  pockets  will  be  spaced  where  the  knobs  are 
to  come  and  above  all  outlets  in  the  ceiling. 

In  order  not  to  complicate  the  directions  at  this 
point,  it  will  be  better  to  read  to  the  end  of  this 
chapter  before  actually  cutting  any  flooring.  In 
this  way  the  exact  points  where  the  knobs  are  to 
come  will  be  better  understood. 


^F 


i 

X 

G 


i 
i 

X 
F 


FIG.  6 


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¥cl] 


'C 

-XD 


X 


J] 


X 


/ 


r 


x 

F 


R 


i-£ 


FIG.  7 


A 
-X- 


-««« 


X 
D 


B 


WIRING   A    HOUSE 


17 


The  exact  places  where  the  ceiling  outlet  pockets 
are  to  be  taken  up  will  be  found  marked  by  the  bit 
which  was  driven  up  through  the  ceiling,  but  the 
other  points  will  have  to  be  determined  on  survey- 
ing the  route  and  will  be  determined  by  the  dis- 
tance between  outlets  as  is  explained  in  the  para- 
graphs on  knobs  and  their  use. 

The  manner  of  opening  a  pocket  in  a  matched 
wood  floor  is  first  to  bore  a  one  quarter  inch  hole 
for  the  keyhole  saw  through  the  joint  between  two 


Fig.  8. 


boards  and  as  near  the  joist  as  possible.  The 
joist  may  be  located  by  the  nails  through  the 
flooring. 

If  blind  nailed  bore  a  hole  by  guess  after  tapping 
the  floor  and  locating  as  near  to  the  joist  by  the 
dull  sound.  Then  bend  a  short  length  of  wire  and 
inserting  it  through  the  hole  fish  around  for  the 
joist.  A  little  practice  will  reveal  to  the  touch 
the  distance  of  the  joist  by  the  resistance  to  the 
bent  wire. 

Having  bored  the  small  hole,  force  in  the  end  of  a 


is 


WIRING   HOUSES 


key  hole  saw  and  cut  across  the  board  at  an  angle 
as  shown  by  the  dotted  lines  in  Fig.  8.  This  is 
to  permit  of  the  board  being  replaced  neatly  after 
the  wiring  is  completed.  Having  sawed  across  the 
piece  of  board  at  both  ends  in  a  similar  manner  it 
may  be  pried  out  using  a  chisel  as  shown  at  B 
in  Fig.  9.  If  it  be  a  hard  wood  floor  it  is  better  to 
saw  first  down  with  the  grain  between  the  boards 
cutting  off  the  tongue  of  the  adjacent  board  as 
shown  at  B.     This  makes  it  easier  to  pry  the 


-'©||KH*WJJiMJJJ|Uliii\ 


Fig.  9. 


board  up  without  splitting  off  the  top  tongue  C 
of  board  D  as  would  be  the  case  if  the  chisel  were 
bent  down  hard  at  A. 

When  taking  up  a  complete  board  insert  the 
chisel  always  on  the  side  B  and  leave  a  second 
chisel  in  to  act  as  a  wedge  when  removing  the  first 
chisel  to  pry  at  a  new  place  further  along.  Some- 
times several  flat  wedges  or  chisels  may  be  used 
in  this  manner  or  an  assistant  can  be  of  service. 
Taking  up  the  first  board  in  every  case  is  the 
hardest,  a  second  adjacent  board  is  easier  to  take 


WIRING   A   HOUSE  19 

up  than  the  first.  Always  lay  the  pieces  near  the 
hole  from  which  they  are  taken  or  mark  them  so 
that  they  may  be  put  back  again.  The  chisel 
used  should  be  at  least  one  inch  broad  and  better  if 
it  is  wider  as  the  distribution  of  leverage  will  ensure 
lighter  markings  on  the  edges  of  the  boards. 

When  all  pockets  are  open  and  all  necessary 
boards  taken  up,  the  boring  and  tubing  of  the  holes 
through  the  joists  may  be  undertaken. 

Boring  and  Tubing.  In  boring  the  holes  through 
the  joists  they  should  be  located  about  two  inches 
from  the  top  of  the  joist.  As  they  will  be  bored 
from  above  they  will  slant  a  trifle  but  this  cannot 
be  helped  and  will  only  require  a  little  more  wire 
and  be  harder  to  pull  the  wires  through  than  if  the 
holes  could  be  bored  straight  and  level. 

These  holes  should  be  bored  with  an  %i  inch 
Ford  bit  or  other  single  cutter  bit  so  that  they  will 
accomodate  tubes  %  inches  outside  and  jjjg  inch 
hole.  If  a  tighter  fit  is  desired  use  f  inch  bit.  It 
is  better  to  have  the  tubes  fit  tight  as  they  will 
not  slip  out  through  jarring  or  when  pulling  the 
wires  through  them.  The  latter  is  usually  done  so 
that  the  pulling  wire  tends  to  pull  the  tube  head 
into  the  hole  and  not  the  other  way.  The  matter 
of  bits  is  taken  up  in  the  later  section  on  tools  and 
material.  There  will  be  probably  a  lot  of  holes 
to  bore  but  a  clean  sharp  bit  and  application  will 
finish  the  job. 

In  boring  these  joist  holes  an  extension  is  a  handy 


20 


WIRING    HOUSES 


tool,  this  is  a  steel  rod  which  fits  into  the  brace 
and  holds  the  bit  lengthening  the  latter.  These 
extensions  may  be  bought  of  several  convenient 
lengths. 

The  two  holes  for  one  circuit  should  not  be  closer 


Fig.  10. 


than  five  inches  to  one  another  and  better  if  still 
further  apart. 

The  appearance  of  a  portion  of  the  floor  with  the 
tubes  and  wires  installed  is  shown  in  Fig.  10. 

There  being  two  wires  it  is  necessary  here  to  take 
up  two  boards  in  order  to  have  room  enough  to 


WIRING  A   HOUSE  21 

work  in.  A  is  a  joist,  T  T  two  tubes  and  W  W 
two  wires  while  B  and  C  are  the  boards  continuing 
those  which  have  been  taken  up.  The  wires  being 
pulled  in  the  direction  of  the  arrow  pull  the  tubes 
into  the  holes  the  heads  being  on  the  side  of  the 
joists  not  shown.  If  pulled  against  the  direction 
of  the  arrow  there  is  a  liability  of  pulling  out  the 
tubes.  Of  course  it  is  a  small  job  to  push  them 
back  again  but  doing  so  means  handling  the  wires 
after  they  have  been  stretched  and  this  is  not  to 
be  done  more  often  than  is  necessary  by  one  in- 
expert in  wiring  work. 

Where  two  joists  come  together  as  where  the  end 
of  one  overlaps  the  end  of  another,  a  long  tube 
must  be  used  sufficiently  long  enough  to  pass  com- 
pletely through  both  joists.  Details  such  as  these 
will  readily  suggest  themselves  to  the  careful  worker 
who  studies  the  work  as  it  progresses. 

Running  the  Circuits.  Having  now  bored  all 
the  holes  and  tubed  those  in  the  joists,  place  the 
knobs  after  which  the  actual  running  of  the  wires 
may  be  proceeded  with. 

Nails  and  Nail-heads.  For  fastening  knobs 
to  the  wood  work,  screws  may  be  used  but 
stout  wire  nails  are  cheaper  quicker  and  satis- 
factory. 

In  order  to  avoid  hitting  the"  porcelain  with  the 
hammer  while  driving  the  nail  home,  leather 
nail-heads  arc  slipped  on  the  nail.     These  are  small 


22  AVI  RING   HOUSES 

washers  of  belt  leather  and  lying  under  the  head 
of  the  nail  act  as  a  cushion  between  the  hammer 
and  the  porcelain.  Leather  nail-heads  may  be 
purchased  from  any  electrical  supply  store  or  cut 
from  a  piece  of  old  leather. 

Knobs  and  Their  Use.  The  form  of  porcelain 
insulator  or  knob  used  in  this  class  of  wiring  is 
known  as  the  No.  5  or  5|  and  is  described  and  shown 
in  the  section  on  materials.  What  are  known  as 
split  knobs  are  also  there  described. 

The  general  spacing  between  knobs  along  the 
joists  is  4|  feet  but  will  vary  according  to  cir- 
cumstances. The  pockets  intended  for  use  in  plac- 
ing knobs  between  outlets  are  taken  up  in  ac- 
cordance with  this  spacing  but  may  vary.  Some- 
times by  extending  this  spacing  a  trifle  only  one 
knob  is  needed  between  two  outlets  and  only  one 
pocket  is  therefore  required. 

A  study  of  this  condition  will  save  work  and 
knobs  but  remember  not  to  save  labor  and  ma- 
terial to  the  detriment  of  the  job.  A  portion  of 
the  floor  showing  three  pockets  with  the  knobs 
and  wire  installed  is  given  in  Fig.  1 1 . 

There  is  no  attempt  in  these  diagrams  to  give 
exact  distances  or  measurements  as  the  width  of 
floor  boards  and  other  conditions  vary. 

Wire.  The  copper  wire  used  in  wiring  inside 
the  house  must  be  rubber  covered  and  protected 
by  a  cotton  braid  and  of  the  size  to  be  selected 


WIRING   A    HOUSE 


23 


according  to  the  data  given  elsewhere.  This  wire 
is  suitable  to  use  in  moulding  or  concealed  in  the 
flooring  when  strung  between  porcelain  knobs,  or 
pulled  in  between  walls  having  first  been  incased 
in  some  form  of  flexible  tube  such  as  Circular  Loom 
or  Flcxduct. 

It  must  not  be  used  outdoors  where  it  will  be 
exposed  to  rain  or  snow  but  the  so-called  weather- 
proof wire   with   a   braided   covering   used   in   its 


Fig.  11. 


stead.  Although  the  latter  form  of  insulation  is 
never  as  good  as  rubber  yet  outdoors  it  does  not 
crack  or  rot.  It  is  never  run  in  wood  mouldings 
but  is  always  supported  on  knobs  or  glass  insu- 
lators. 

Details  of  wire  are  given  in  the  section  on 
materials. 

The  best  method  of  handling  the  wire  is  to  take 
the  coil  and  divide  it  into  two  equal  coils.     This 


24  WIRING   HOUSES 

enables  both  sides  of  the  circuit  to  be  run  practi- 
cally at  the  same  time. 

For  the  present  leave  these  two  coils  at  the  point 
where  it  is  intended  to  drop  the  two  service  ends 
down  in  the  wall  to  the  service  switch  in  the 
cellar. 

Take  two  ends  from  each  coil,  or  one  at  a  time 
as  preferred  and  with  care  so  that  they  do  not 
kink,  start  these  ends  under  the  floor  through 
the  nearest  pocket  and  under  the  floor  from  pocket 
to  pocket  and  through  the  tubes  until  the  extreme 
end  of  the  circuit  is  reached.  Considering  Fig.  7, 
the  coils  will  be  left  at  D  (or  at  E)  and  the  ends 
run  under  the  floor  past  each  outlet  until  outlet  F 
is  reached.  Then  making  fast  at  F,  the  wires  may 
be  stretched  and  fastened  to  the  knobs  returning 
along  the  route  until  the  other  end  of  the  circuit 
at  D  or  E  is  reached,  there  being  then  the  re- 
mainder  of   the   wire   lying  in  two   coils. 

They  will  not  be  pulled  down  into  the  cellar  at  E 
yet  but  at  a  later  time  as  will  be  seen  farther 
on. 

The  ends  at  the  farther  ceiling  outlets  F  may  be 
left  long  enough  to  pass  down  through  the  ceiling 
hole  and  leave  at  least  8  inches  for  connection  to 
the  fixture. 

On  straight  runs  or  when  running  one  circuit  it 
is  a  good  plan  to  place  all  the  knobs  first  then  the 
wires  can  be  pulled  tight  from  the  extreme  end 
knob  and  fastened  to  the  knobs  as  the  circuit  is 
followed. 


WIRING   A   HOUSE 


25 


The  run  will  be  past  each  outlet  as  far  as  possible 
but  no  outlet  wires  will  be  tapped  on  yet,  this  will 
be  done  when  the  entire  length  of  wire  has  been 
fastened  under  the  floor  to  the  knobs. 

Making  Fast.  When  making  fast  from  knob  to 
knob  the  wire  may  either  be  given  a  turn  around 
the  intermediate  knobs  being  held  tight  at  the  end 
knobs  by  a  dead-end  hitch  or  what  is  better  be 


Figs.  12  and  13. 


tched  at  each  knob  as  shown  in  Fig.  12.  This 
lakes  more  wire  and  a  little  more  practice  but  keeps 
the  wire  tight  between  ail  knobs  instead  of  only 
between  those  to  which  it  is  dead-ended  or  hitched. 
The  principal  objection  to  these  methods  as  against 
tie  wires  is  that  should  the  wire  come  off  the  knob 
the  hitched  or  twisted  part  would  slacken  and 
allow  the  wire  to  touch  the  woodwork. 


26  WIRING   HOUSES 

A  good  method  is  to  fasten  a  few  knobs  on  a. 
board  and  practice  the  hitches  and  other  methods 
of  securing  wires  the  advantages  of  the  several 
methods  will  then  be  apparent  and  the  practice 
useful  when  actually  engaged  in  wiring  up  the 
house. 

The  method  of  tying  a  wire  to  a  knob  using  tie 
wires  is  shown  in  Fig.  13  from  a  photograph.  The 
tie  wire  is  a  separate  piece  about  fifteen  inches  long 
and  is  first  tied  around  the  knob  and  main  wire  so 
as  to  secure  the  latter  to  the  knob.  The  loose  ends 
are  then  twisted  around  the  main  wire  one  end  on 
each  side  of  the  knob.  The  hitch  or  tie  is  made  by 
using  the  middle  portion  of  the  tie  wire  leaving  two 
ends  of  about  the  same  length. 

Another  method  which  is  not  so  good  is  to  merely 
wrap  the  tie  wire  around  the  main  wire  and  the 
knob  and  twist  on  the  ends.  The  hitch  although 
taking  more  wire  and  more  time  is  to  be  preferred 
in  all  cases. 

Where  a  circuit  ends  at  an  outlet  two  methods 
may  be  pursued.  The  wires  may  be  dead  ended 
and  short  pieces  for  the  outlet  be  tapped  on, 
this  makes  a  firm  job  but  requires  a  soldered 
joint.  Or  the  ends  of  the  wire  may  be  left  long 
enough  to  reach  down  through  the  outlet  after  the 
wires  have  been  stretched  and  made  fast  by  means 
of  the  dead-end  method  elsewhere  illustrated. 
The  latter  is  the  usual  method  where  the  wires  can 
be  ended  near  the  outlet  but  sometimes  it  is  not 
practicable  to  end  them  near  the  outlet. 


WIRING    A   HOUSE 


27 


Where  two  circuits  cross  each  other  or  where 
one  wire  of  a  tap  crosses  the  other  main  wire,  a 
porcelain  tube  should  be  slipped  over  the  crossing 
wire  or  wires  as  shown  in  Fig.  14.  There  should 
be  placed  two  knobs  each  side  of  the  crossed  wires 
as  shown  in  order  to  secure  the  crossing  wire  and 
the  tubes.  These  knobs  are  often  omitted  and 
the  tubes  merely  held  fast  to  the  wire  upon  which 
they  are  slipped  by  means  of  tape  but  the  above 
is  preferable. 


Fig.  14. 

All  branch  or  tap  wires  must  be  secured  to  a  knob 
at  the  point  where  they  are  led  off  from  the  main 
circuit  as  at  outlets,  these  knobs  however  need 
not  be  installed  now  but  when  making  the 
taps. 


Joints.  The  two  joints  used  in  electrical 
wiring  are  the  splice  and  the  tap.  The  splice  as  its 
name  implies  is  used  where  two  pieces  of  wire 
are  to  be  joined  together  in  the  direction  of  their 


28 


WIRING    HOUSES 


length.     The  tap  is  used  where  a  branch  wire  is  to 
be  run  of!  another  wire  at  right  angles  to  it. 

There  are  two  methods  of  making  splices,  by- 
twisting  the  wires  together  and  by  using  patent 
screw  unions  or  Dossert  joints.  Taps  are  also 
made  by  twisting  one  wire  on  to  the  other  or  by 
Dossert  taps.  Furthermore  there  are  several 
pieces  of  apparatus  such  as  fuse  blocks  and  cutouts 


Fig.  15. 


in  which  wires  are  joined  through  screw  connections 
or  under  screwed  lugs  and  several  ingenious  de- 
vices for  special  conditions. 

The  first  and  simplest  methods  of  twisting  wires 
will  be  described  here. 

The  illustrations  showing  splices  and  the  methods 
of  fastening  wires  have  been  made  from  photo- 
graphs of  the  actual  work  making  the  operations 
clearer  than  could  be  done  by  drawings. 


Making  a  splice  joint. 


The  splice  ready  for  solde 


A  tap  ready  for  soldering. 


PL  \TK  111. 


WIRING    A    HOUSE  29 

In  Fig.  15  is  the  method  of  making  a  splice.  The 
wire  is  bared  of  its  insulation  for  three  inches  and 
the  two  pieces  laid  together  and  bent  as  shown. 
Then  the  two  bare  wires  are  twisted  together  the 
ends  shown  loose  being  either  worked  in  with  the 
pliers  or  cut  off  close.  A  method  often  pursued 
is  to  twist  the  wires  tighter  together  each  turn 
lying  close  up  to  its  neighbor,  but  the  looser  twist 
gives  a  better  means  for  applying  the  solder.     With 


Fig.  16. 

the  close  coiling  the  solder  is  liable  not  to  penetrate 
the  wire  turns  but  where  the  turns  are  well  apart 
it  can  enter  more  readily. 

The  method  of  making  a  tap  is  shown  in  Fig.  16 
from  a  photograph.  A  knob  is  placed  where  the 
tap  wire  is  to  lead  off  from  the  main  wire.  The 
latter  is  then  bared  of  its  insulation  a  few  inches 
from  this  knob  and  scraped  bright. 

The  tap  wire  is  also  bared  and  scraped  bright 
for  three  or  four  inches  at  its  end  and  fastened 


30  WIRING   HOUSES 

around  the  knob  so  as  to  hold  the  main  wire  to  the 
insulator.  This  is  done  by  making  a  hitch  with 
the  tap  wire  while  putting  it  in  place.  The  loose 
(Mid  is  wrapped  around  the  insulated  portion  of  the 
main  wire  and  twisted  around  the  bare  spot  as 
shown . 

This  method  secures  the  main  wire  to  the  knob, 
secures  the  tap  wire  to  the  knob  and  to  the  main 
wire  before  it  gets  to  the  bare  spot  and  takes  all 
strain  off  the  joint  and  the  main  wire.  The  hitch 
is  not  drawn  tight  in  the  illustration  to  better  show 
the  details  of  the  operation. 

In  the  same  figure  is  illustrated  the  best  method 
of  making  a  dead-end.  This  is  the  end  of  this 
circuit  and  the  end  of  the  wire  is  hitched  around 
the  knob,  then  the  loose  end  wrapped  around  the 
tight  wire.  This  is  better  than  merely  giving  the 
wire  a  turn  or  two  around  the  knob  and  twisting 
up  the  ends. 

Soldering.  All  joints  made  in  wires  which  are  to 
carry  current  should  be  soldered  in  order  to  make 
good  electrical  contact.  Unsoldered  joints  are 
both  dangerous  and  unreliable.  In  the  first  place 
unsoldered  joints  will  corrode  from  dampness  and 
by  reducing  the  bare  clean  copper  surface  raise 
the  resistance  of  the  joint  so  that  it  may  become 
fieated.  In  the  case  of  110  volt  installations  the 
resistance  of  a  poor  joint  might  not  be  apparent 
in  the  light  but  where  the  voltage  is  low  the  resist- 
ance of  the  poor  joint  is  a  serious  matter. 


WIRING   A    HOUSE  31 

Poor  joints  are  the  cause  of  fires  in  many  cases 
and  it  must  be  impressed  here  that  all  joints  carry- 
ing current  must  be  above  reproach.  Remember 
that  an  unsoldered  joint  or  any  poor  work  in  fact 
does  not  improve  with  time  but  becomes  worse, 

As  there  will  be  a  number  of  joints  to  solder  in 
wiring  up  a  house,  it  is  best  to  leave  them  until  as 
many  as  possible  are  ready  for  soldering.  It  is 
then  a  quick  job  to  go  from  joint  to  joint  and  solder 
up.  The  soldering  torch  need  not  be  lighted  and 
extinguished  more  often  than  necessary. 

The  soldering  torch  used  will  depend  upon  what 
is  available  unless  it  is  desired  to  buy  one.  If  none 
is  at  hand  a  small  alcohol  torch  or  blowpipe  may 
be  bought  for  about  a  dollar  and  will  answer  all 
practical  purposes.  A  flame  that  gives  smoke 
will  not  do  to  solder  with,  alcohol  or  gasoline  used 
in  a  proper  torch  are  the  best.* 

Together  with  the  lamp  will  be  needed  some  wire 
solder  or  shoestring  solder  and  some  kind  of  flux. 
There  are  several  good  kinds  on  the  market  called 
generally  "  soldering  paste  "  and  any  electrical  or 
hardware  store  can  supply  them.  So  called  solder- 
ing salts  made  of  muriatic  acid  and  zinc  should 
never  be  used  as  unless  the  last  trace  has  been 
washed  off  the  joint  it  will  surely  corrode  in 
time. 

A  small  quantity  of  the  paste  should  first  be  put 
on  the  joint  which  is  then  h'eated  with  the  torch 

*  See  Thatcher,  Simple  Soldering  both  Hard  and  Soft. 


32  WIRING    HOUSES 

flame  and  the  solder  held  to  it  until  it  melts  and 
runs  thoroughly  into  all  the  crevices  of  the  joint. 
If  the  wire  is  not  hot  and  the  solder  run  in  well,  the 
joint  will  be  bad  and  surely  cause  trouble.  Try  the 
first  job  as  soon  as  the  solder  is  set  and  if  it  peels 
off  either  the  paste  was  not  sufficient  or  the  wire  was 
not  hot  enough.  Soldering  with  a  clean  joint, 
good  paste  and  a  hot  flame  is  by  no  means  a  diffi- 
cult process. 

Taping.  After  soldering  the  joint,  or  tap,  it 
must  be  covered  with  an  insulation  equal  to  that 
removed  for  a  weak  spot  of  insulation  at  any  point 
is  bad. 

A  few  inches  of  the  rubber  tape  is  cut  off  the 
roll  and  twisted  tightly  around  the  joint  while  it  is 
hot.  If  it  has  cooled  it  should  be  again  heated. 
It  will  be  found  that  the  heat  will  melt  the  rubber 
and  it  will  adhere  to  the  joint  to  which  it  is  to  be 
moulded  with  the  fingers.  Then  the  friction  or 
adhesive  tape  is  wound  over  the  joint  covering  the 
wire  entirely  from  a  few  inches  back  of  the  joint  to 
an  inch  or  so  beyond  it. 

No  bare  spots  may  show  at  any  place  but  all 
metal  must  be  covered  neatly  with  rubber  tape 
and  with  friction  tape. 

Ceiling  Outlets.  In  order  to  have  a  secure  hold 
for  the  screws  used  in  fastening  up  the  fixtures, 
ceiling   boards,   B,   Fig.    17   are   placed   at   every 


WIRING   A   HOUSE 


33 


ceiling  outlet.  A  piece  of  f  board,  soft  pine  pre- 
ferably is  cut  just  long  enough  to  fit  between  the 
joists  /  J  and  about  6  inches  wide.  Wire  nails  are 
then  driven  part  way  through  the  board  near  the 
edge  in  a  diagonal  direction  and  the  board  laid  in 
place  so  that  its  centre  comes  just  over  the  small 
hole  made  by  the  bit.  It  is  then  nailed  fast  using 
great  care  not  to  hit  it  so  that  the  plaster  falls  from 
the  ceiling   C. 


Fig.  17. 


It  is  not  hard  to  fix  these  ceiling  boards  if  the 
nails  are  driven  carefully  and  diagonally,  using  a 
nail  not  over  one  inch  and  a  half  or  two  inches  long. 
A  little  experimenting  first  will  show  the  correct 
way  to  nail  the  board,  it  is  easy  after  the  correct 
way  is  learned  but  pages  of  directions  would  not 
make  it  any  clearer. 

Having  put  ceiling  boards  in  place  at  every  out- 
let, go  down  stairs  and  with  the  bit  used  in  boring 


34  WIRING   HOUSES 

for  the  tubes,  bore  up  through  the  ceiling  at  the 
point  where  the  small  bit  went  through.  Two 
holes  must  be  bored  but  each  diagonally  upwards 
in  such  manner  that  they  make  two  diagonal 
holes  through  the  ceiling  board  but  enly  one  hole 
in  the  ceiling  plaster  below.  The  idea  is  that  the 
two  pieces  of  loom  each  covering  one  wire  are  to 
start  down  through  practically  separate  holes  in 
the  ceiling  board  but  to  come  together  through  one 
hole  in  the  ceiling.  This  is  shown  in  a  later  il- 
lustration (Fig.  25). 

After  studying  this  out  it  will  be  seen  to  be  very 
simple  as  the  loom  is  flexible  and  two  ends  can  be 
flattened  a  trifle  to  come  out  through  one  %  inch 
hole  in  the  plaster.  If  the  operator  prefers  he  may 
bore  one  hole  straight  up  and  cut  the  board  away 
to  allow  the  two  pieces  of  loom  to  pass  through, 
or  bore  the  ceiling  hole  first,  then  make  a  large 
hole  in  the  ceiling  board  before  nailing  it  in  place. 
But  the  first  method  is  the  best  and  really  the 
simplest. 

It  may  be  remarked  here  that  the  wires  coming 
down  through  the  ceiling  outlets  for  the  fixtures 
will  be  separate  pieces  cut  to  length  and  tapped  on 
to  the  circuit  separately  except  perhaps  at  the 
extreme  end  where  enough  may  be  allowed  when 
tying  to  drop  down  at  this  one  outlet. 

After  having  installed  the  ceiling  boards,  pieces 
of  lumber  say  one  inch  thick  and  two  inches  wide, 
are  nailed  on  along  the  joist  just  below  the  opening 
as  shown  at  5  S.     These  pieces  are  to  hold  the 


WIRING   A   HOUSE  35 

pieces  of  flooring  when  the  latter  are  relaid  as  is 
shown  in  a  later  illustration  (Fig.  25). 

Looming  the  Wire.  Having  now  reached  the 
coiled  wire  measure  enough  to  reach  clear  down 
into  the  cellar  and  leave  enough  additional  to 
reach  the  switchboard,  then  cut  loom  encugh  to 
cover  the  wires  from  the  last  knob  upstairs  to  the 
entrance  into  the  cellar  and  slip  it  on  the  wires. 
This  of  course  applies  to  both  wires  of  the  circuit. 

This  loom  or  "  circular  loom  "  is  a  flexible  in- 
sulating tube  made  in  several  varieties  and  called 
by  various  trade  names.  Circular  loom  and 
Flcxduct  are  the  two  best  known  and  are  suitable 
for  use  here.  They  are  costly  however  and 
measurements  should  be  made  before  buying,  the 
average  cost  being  about  5  cents  a  foot  or  10  cents 
for  the  two  wires. 

The  wire  is  inserted  in  the  tube  and  should  be 
shoved  in  little  by  little  taking  a  grip  on  the  wire 
between  the  first  finger  and  the  thumb  a  few  inches 
from  the  opening  of  the  loom.  At  first  the  wire 
will  slip  in  easily  but  after  a  while  it  may  stick, 
when  the  loom  should  be  shaken  as  a  terrier  shakes 
a  rat.  If  an  assistant  holds  the  far  end  of  the  loom 
when  feeding  in  long  wires,  he  can  shake  it  con- 
tinually and  the  wire  will  slip  in  the  more  easily. 
The  sizes  of  loom  suitable  for  different  wires  are 
given  in  the  section  on  materials. 

Wiring  in  Attics.     The  wiring  for  the  fixtures  on 


36  WIRING   HOUSES 

the  second  floor  will  be  done  in  the  attic.  Wiring 
in  attics  is  done  with  consideration  as  to  whether 
there  is  any  possibility  of  the  attic  being  used  for 
other  than  a  space  between  the  roof  and  the  ceiling. 
Where  the  attic  is  too  small  for  other  use  and  there 
is  no  possibility  of  persons  entering  it  except  for 
stringing  wires,  or  where  it  cannot  be  used  for 
storage  purposes,  as  in  many  bungalows,  the  wiring 
may  be  installed  on  the  floor  beams  without  boring 
or  tubing  them  but  by  running  the  wires  on  knobs. 
But  where  there  is  any  possibility  of  the  attic  being 
used  the  wires  should  be  installed  by  boring  and 
tubing. 

The  installation  of  the  wiring  for  the  second 
floor  then  will  probably  be  easier  than  that  for  the 
first  floor  as  there  will  be  less  cutting  of  boards  and 
perhaps  none.  The  layout  can  be  made  easily  as 
here  will  be  no  partitions  to  obstruct  the  view  and 
the  flooring  if  any  will  not  be  hard  wood  matched 
but  plain  boards. 

The  ends  of  this  circuit  may  either  be  tapped  on 
to  the  circuit  on  the  floor  below  or  what  is  better 
in  a  large  house,  run  clear  to  the  service  and  there 
connected  to  a  separate  cut-out  or  switch,  details 
of  which  will  be  given  in  the  section  on  service 
switches. 


CHAPTER  III. 


Completing  the  Installation. 

Wiring  to  the  Service  Switch.  The  service  or 
main  switch  will  in  the  majority  of  cases  be  in  the 
cellar  or  lower  part  of  the  house.  The  ends  of  the 
circuit  wires  which  have  been  measured,  cut  and 
protected  by  loom  are  now  ready  to  be  pulled  down 
for  attachment  to  this  switch.  This  may  be  done 
now  or  after  the  outlet  wires  have  been  tapped  on. 
Whatever  will  save  time  labor  and  going  up  and 
down  stairs  is  worthy  of  consideration  and  will 
determine  the  time  for  each  operation. 

In  frame  houses  there  will  be  found  a  space  be- 
tween the  lath  and  plaster  of  the  walls  and  the 
outside  boards  of  the  house  in  which  space  the 
wires  may  be  pulled  down.  Generally  this  space 
extends  clear  from  the  attic  floor  to  the  cellar 
ceiling  and  a  lead  weight  called  a  mouse  tied  on  a 
stout  cord  may  be  dropped  clear  down  to  the  cellar 
from  above.  In  some  houses  where  the  floor  has 
been  laid  in  continuous  lengths  the  space  will  be 
blocked  but  removal  of  the  mop  board  and  the 
boring  of  a  couple  of  holes  will  remedy  this.  A 
joist  or  "  plate "  will  also  be  frequently  found 
blocking  the  way  and  must  be  bored. 

Having  dropped  the  weight  down  in  this  space 

37 


38  WIRING    HOUSES 

and  secured  the  free  end  of  the  cord  to  the  wires, 
the  weight  may  be  found  down  in  the  cellar  prob- 
ably resting  on  top  of  the  cellar  wall  and  the  wires 
pulled  down  by  its  aid. 

It  is  a  hard  job  for  a  novice  to  pull  wires  down 
alone  and  an  assistant  is  of  service  upstairs  who  can 
feed  the  loomed  wires  down  and  keep  them  from 
kinking  while  they  are  being  pulled  down.  It  is  a 
peculiar  fact  that  if  there  is  a  nail  or  any  projection 
upstairs  any  where  near  the  wires  while  they  are 
being  pulled  down  that  they  are  almost  sure  to 
catch  on  it.  The  pull  should  be  steady  and  careful 
as  although  the  loomed  wire  will  stand  a  consid- 
erable strain  there  is  no  need  of  using  more  force 
than  necessary. 

The  wires  having  been  pulled  into  the  cellar  are 
ready  for  attachment  to  the  service  switch. 

Where  the  service  is  in  the  attic  the  weight  is  to 
be  dropped  down  in  the  same  manner  and  the  wires 
pulled  up.  As  this  is  a  harder  job,  sometimes  it  is 
better  to  pull  down  a  separate  pair  of  wires  and  tap 
them  on  to  the  main  circuit  which  is  first  dead- 
ended. 

The  Service  or  Main  Switch.  Where  the  bat- 
tery plant  and  the  switchboard  are  located  in  the 
house  the  circuit  wires  will  probably  be  led  di- 
rectly to  this  switchboard  and  controlled  from  it 
by  means  of  a  switch  or  switches.  But  if  the  plant 
is  in  another  building  the  wires  leading  from  it  will 
then  run  to  a  main  or  service  switch  located  in  the 


COMPLETING   THE    INSTALLATION  39 

house  to  which  likewise  the  house  circuit  wires  will 
also  connect. 

Considering  then  that  the  battery  or  service 
wires  are  run  in  from  outside  it  is  best  to  install 
a  service  switch  and  fuse  block.  As  also  in  the 
case  of  a  large  house  the  wiring  will  be  divided  into 
perhaps  two  or  more  circuits,  there  will  be  neces- 
sary more  than  one  fuse  block  and  if  desired  a 
switch  to  control  each  circuit.  The  service  wires 
will  run  to  the  service  switch  and  cut-out  first. 
The  best  plan  is  to  make  up  a  box  to  hold  the 
switches  and  fuse  blocks. 

The  size  of  the  box  will  depend  upon  what  it  is 
to  hold  of  course  but  it  must  be  large  enough  to 
hold  all  the  apparatus  with  the  switches  either  open 
or  closed.  It  should  be  made  from  §  inch  lumber 
and  be  not  less  than  3|  inches  deep,  provided  with 
a  door  which  should  be  hinged  from  above  so  that 
the  weight  of  the  lid  will  always  keep  it  closed. 
After  having  been  well  painted  within  and  without 
with  a  good  moisture  repelling  paint,  it  should  be 
lined  entirely  on  the  inside  with  either  sheet  iron 
or  sheet  asbestos  and  the  asbestos  again  painted. 
This  will  keep  it  dry  and  prevent  any  liability  of 
fire  from  a  blown  fuse  or  from  other  causes.  The 
holes  through  which  the  wires  pass  should  be 
bushed  with  porcelain  tubes,  loom  is  sometimes  used 
but  is  not  suitable  in  damp  places. 

The  usual  form  of  main  switch  is  known  as  a 
double  pole,  single  throw,  knife  switch  and  of  an 
ampere  carrying  capacity  as  required.     Generally 


40  WIRING   HOUSES 

for  a  small  house  with  a  few  lights  this  switch  will 
be  of  15  to  25  ampere  capacity  but  a  larger  one  is 
no  detriment. 

The  fuse  block  or  cut-out  may  be  one  with  cart- 
ridge fuses  or  what  is  suitable  for  the  low  voltage 
circuits,  with  Edison  screw  plug  fuses  as  in  Fig.  18. 

The  wires  from  the  battery  should  go  to  the  fuse 
block  or  cut-out  first  and  the  house  circuit  wires  to 
the  switch.  This  allows  the  fuses  to  protect  the 
entire  circuit  and  the  switch,  if  the  switch  should 
happen  to  be  short  circuited  by  accident,  it  having 


Fig.  18. 

bare  metal  parts,  the  cut-out  fuses  would  blow. 
But  if  the  outside  wires  led  first  to  the  switch,  a 
short  circuit  on  the  switch  would  not  blow  the 
fuses  there  but  those  at  the  battery  if  there  were 
any.  Note  here  and  in  all  cases  that  a  knife 
switch  must  be  fastened  so  that  it  opens  downwards 
and  not  upwards.  This  is  so  that  it  cannot  drop 
shut  after  being  left  open. 

In  Fig.  19  is  shown  a  diagram  of  a  service  switch 
and  box  where  C  is  the  cut-out  with  its  fuses  and 
S  the  switch.     The  wires  from  the  source  of  elec- 


COMPLETING   THE    INSTALLATION 


41 


tricity  here  come  in  at  the  top  of  the  box  and  the 
house  circuit  wires  leave  from  the  bottom.     This 


Fig.  19. 


is   the    simplest    arrangement    of   a    cut-out    and 
switch. 

In  Fig.  20  is  another  diagram  where  the  house 


42 


WIRING   HOUSES 


circuit  wires  and  the  service  wires  all  lead  out  at 
the  top.  This  is  sometimes  an  advantage  as  the 
wires  may  be  led  away  directly  along  the  cellar 
ceiling  beams. 

A  very  convenient  form  of  25  ampere  service 
switch  for  this  class  of  work  is  that  shown  in  Fig.  21 . 


Fig.  20. 


It  is  self-contained  with  both  the  switch  and  the 
cut-out  and  its  fuses  mounted  on  one  base.  This 
form  of  switch  may  be  installed  on  an  asbestos 
covered  board,  or  even  on  a  board  painted  with 
moisture    repelling    paint    providing    the   location 


COMPLETING   THE    INSTALLATION 


43 


is  not  damp.     But  a  cut-out  box  is  easy  to  make, 
and  is  by  far  a  safer  and  neater  job,  a  lock  and  key 


Fig.  21. 


Fig.  22. 


being  added  giving  greater  protection  against  any 
tampering  with  the  main  switch. 

Where  the  house  is  a  large  one  and  it  is  best  to 


44 


WIRINC,    HOUSES 


divide  the  lights  into  several  separate  circuits 
each  running  to  the  cut-out  box,  the  form  of  com- 
bined switch  and  cut-out  shown  in  Fig.  22  is  very 
suitable  although  for  a  cheaper  job  separate  cut- 
outs and  switches  may  be  used. 


The  arrange- 


A_J, 


Fig.  23. 


ment  shown  has  snap  switches  but  is  also  made  with 
knife  switches  in  a  slightly  different  pattern.  The 
one  illustrated  is  neat  enough  to  use  where  it  is 
exposed  should  it  be  desired  to  put  the  switches 
controlling  such  separate  circuits  in  a  prominent 
place  upstairs. 


COMPLETING    THE    INSTALLATION 


45 


A  service  switch  box  made  up  with  the  self-con- 
tained switch  before  described  is  in  Fig.  23.  This 
box  is  arranged  for  two  house  circuits  but  more  ma  y 
be  added  as  desired. 


Fig.  24. 


The  form  of  service  switch  installed  in  an  iron 
box  shown  in  Fig.  24  is  very  convenient  and  ready 
for  attachment  to  the  wires.  The  switch  is  self- 
contained  having  plug  fuses. 


CHAPTER  IV. 


Installing  Lights. 


The  Outlet  Wires.  The  outlet  wires  may  be 
tapped  on  now  that  the  wires  are  in  place  and 
secured  fast.     Pieces  of  wire  long  enough  to  reach 


Fig.  25. 


down  through  the  outlet  holes  about  eight  inches 
and  wrap  around  the  knob  and  the  main  wire  are 
cut  off  from  the  coil  or  odd  short  pieces  are  used. 
Before  cutting  them  it  will  be  well  to  fully  under- 

46 


INSTALLING   LIGHTS  47 

stand  how  they  are  placed  so  that  they  may  be  cut 
to  suit  the  location. 

As  in  Fig.  25  the  outlet  wire  is  tied  around  the 
knob  K,  the  short  end  bared  and  tapped  on  to  the 
main  wire  and  a  piece  of  loom  slipped  on  after 
which  it  is  ready  to  be  thrust  down  through  the 
outlet  hole.  Tying  it  in  this  manner  secures  both 
the  short  piece  and  the  main  wire  and  takes  the 
strain  off  the  joint.  Leave  the  piece  too  long  rather 
than  short.  In  cutting  the  outlet  wire  cut  it  long 
enough  as  it  is  easier  to  push  up  the  slack  from 
below  or  cut  a  piece  off,  than  to  splice  a  short 
wire. 

Installing  the  Lights.  Every  joint  having  been 
soldered  and  taped  and  all  wires  in  place  the  next 
operation  is  the  last,  that  of  connecting  on  the 
sockets  or  the  fixtures.  This  is  done  after  all 
wires  are  ready  and  the  floor  boards  back  in  place, 
being  generally  a  quick  job. 

Whether  there  will  be  regular  fixtures  or  merely 
drop  lights  is  a  matter  to  be  decided  by  the  reader, 
but  as  the  drop  light  is  the  cheaper  and  used  very 
generally  they  will  be  next  considered. 

Drop  Lights.  In  many  places  such  as  bath- 
rooms, bedrooms  and  the  kitchen,  a  drop  light  will 
suffice  and  save  the  cost  of  a  fixture.  Drop  lights 
are  made  up  in  two  ways,  with  fuses  and  without. 
The  best  plan  is  to  make  them  up  unfused  and 
have  the  fuses  in  the  cut-out  box. 


48 


WIRING   HOUSES 


A  drop  light  comprises  three  parts,  the  rosette, 
the  cord  and  the  socket,  to  which  of  course  must 
be  added  the  lamp.  The  rosette  is  the  device 
by  which  the  cord  is  attached  to  the  main  wires  and 
also  which  supports  the  cord  and  lamp.  It  is  of 
porcelain  and  has  screws  and  lugs  for  attachment 
of  the  cord  and  the  main  wires,  the  fused  rosettes 
being  made  in  two  readily  separable  parts. 

The  form  of  rosette  shown  in  Fig.  26  is  made  to 


Fig.  26. 


Fig.  27. 


take  a  fuse  and  is  used  in  concealed  work  where 
the  wires  come  through  the  ceiling. 

Another  type  for  moulding  work  is  shown  in 
Fig.  27  and  a  cleat  type  used  where  the  wires  are 
run  on  cleats  or  otherwise -exposed  is  shown  in 
Fig.  28. 

An  unfused  rosette  is  shown  in  Figs.  29.  Making 
up  rosettes  is  done  the  same  way  as  with  sockets 


INSTALLING   LIGHTS  49 

in  that  a  knot  must  be  made  in  the  cord  to  take  the 
strain  off  the  cord  at  the  connecting  clamps  or 
screws. 

Making  up  a  Drop  Light.  The  cord  may  be 
covered  with  cotton,  silk  or  mohair  as  selected 
the  twisted  cotton  covered  being  the  kind  most 
used.  For  low  voltage  lighting  it  is  suitable  but  is 
not  used  in  good  work  for  regular  110  volt  lighting. 
The  sizes  most  used  for  single  drop  lights  are  No.  16 


Fig.  28.  Fig.  29. 

and  No.  18  B.  &  S.  The  former  will  be  better 
for  low  voltage  work  as  its  resistance  per  foot  is 
less.  For  lengths  of  over  10  feet  No.  14  should  be 
employed. 

The  first  operation  is  to  measure  the  length  of 
cord  necessary  so  that  the  light  will  hang  at  the 
desired  height.  It  should  not  be  left  too  long  as 
although  there  are  plenty  of  cord  adjusting  de- 
vices for  sale  they  all  look  unsightly. 


50  WIRING    II:  lUSES 

Having  cut  the  cord  to  the  right  length  take  a 
socket  apart  as  in  Fig.  30.  Some  sockets  require 
that  screws  be  loosened  before  the  shell  can  be 
removed,  others  of  more  modern  design  are  so  made 
that  a  pressure  on  the  shell  near  the  point  where  it 
is  slipped  in  the  cap  will  loosen  it  so  that  it  readily 
comes  apart. 

A  hard  rubber  socket  bushing  is  screwed  into 
the  hole  in  the  cap  to  prevent  the  insulation  of  the 
cord  becoming  abraded. 

Having  separated  the  socket  into  its  three  parts 


the  cord  may  be  untwisted  for  a  few  inches  and  the 
copper  wires  bared  for  about  three-quarters  of  an 
inch  on  each  part.  The  easiest  way  to  do  this  is  to 
lay  the  cord  on  the  table  and  scrape  off  the  cotton 
and  rubber  insulation.  Then  twist  up  the  loose 
copper  strands  on  both  pieces  so  that  they  will  not 
stray  but  lie  neatly  like  a  solid  wire. 

A  knot  is  then  made  about  an  inch  and  a  half 
from  the  end. 

Loosen  the  screws  on  each  side  of  the  socket  B 


— Rosette  base- 


'j         — Rosette  cap — 


— Socket  cap 

and  bushing- 
— Knot 


-Bared 

Wires 


Wires 
connected- 


— Socket  sbell — 


PLATE  IV 


INSTALLING    LIGHTS  51 

and  twist  the  wires  under  them  once  around. 
Twist  in  the  same  direction  as  the  screw  will  turn 
when  being  tightened  so  that  the  turning  of  the 
screw  will  not  push  out  the  wires. 

Tighten  up  the  screws  and  twist  any  loose  ends 
around  the  wire  above  the  screw. 

Then  slip  the  cap  A  over  the  other  end  of  the 
cord  and  the  shell  C  on  to  the  lower  part  of  the 
socket.  Press  them  together  and  it  will  be  found 
that  the  knot  will  take  the  strain  off  the  screws 
inside  by  catching  against  the  inside  collar  of  the 
cap. 

Great  care  must  be  taken  that  no  loose  strands 
of  wire  are  left  inside  the  socket  or  a  short  circuit 
will  result,  loose  strands  must  be  looked  for  before 
closing  up  the  socket. 

Having  made  up  the  socket  take  the  rosette 
apart  and  thread  the  cord  through  the  hole  in  the 
cap.  The  cord  must  be  inserted  bearing  in  mind 
that  the  cap  will  be  head  downward  from  the 
ceiling.  The  top  end  of  cord  is  then  untwisted  and 
its  ends  bared  as  before,  knotted  and  made  fast 
under  the  screws  in  the  rosette  cap. 

All  the  drop  lights  for  a  job  may  be  made  up  and 
put  up  at  one  time  if  preferred  which  is  the  usual 
way  on  large  jobs. 

When  ready  to  put  up  the  drop  light  the  wires  in 
the  ceiling  are  threaded  through  the  holes  in  the 
rosette  base  and  the  latter  screwed  fast  to  the 
ceiling.  Where  ceiling  boards  have  been  in- 
stalled screws  long  enough  should  be  used  so  that 


rig.  31. 


INSTALLING    LIGHTS  53 

they  penetrate  it,  a  number  6  screw  is  heavy 
enough.  The  wires  are  then  cut  to  length  and 
scraped  clean  and  fastened  under  the  screw 
heads  or  lugs  in  the  rosette  base. 

Fixtures.  The  selection  of  fixtures  is  a  matter 
of  taste.     A  simple  design  is  shown  in  Fig.  31. 

The  recent  introduction  of  high  candlepower 
lamps  with  high  intrinsic  brilliancy  has  starfed  a 
craze  for  what  is  termed  indirect  illumination,  the 
light  being  reflected  from  the  ceiling  and  the 
upper  part  of  the  walls,  and  not  directly  from  the 
lamp. 

This  system  is  all  very  well  where  the  expen- 
diture of  electricy  is  of  little  account,  or  where 
special  effects  are  desired,  but  is  out  of  place  in 
the  home  where  the  cost  of  current  is  an  item. 

The  underlying  idea  is  that  the  direct  light 
hurts  the  eyes,  but  no  heed  is  taken  of  the  fact 
that  the  straining  from  the  poor  quality  of  this 
reflected  light  is  often  worse. 

Unless  the  candlepower  of  the  light  be  very 
great,  or  there  be  many  lights,  the  light  reflected 
from  the  ordinary  ceiling  is  almost  always  in- 
sufficient for  reading,  specially  if  the  reader  has 
any  weakness  of  the  sight,  or  has  failing  eyesight 
due  to  advancing  years. 

Switches.  Switches  are  made  in  man}'  styles 
and  types  to  suit  all  conditions  and  will  be  treated 
of  in  their  place.     It  is,  however,  most  likely  that 


54 


WIRING  HOUSES 


Section  through  ceiling  and  wall. 

Fig.  32. — Wiring  a   drop   light  and  single  pole  switch. 
Dotted  line  is  second  main  wire. 


INSTALLING    LIGHTS  55 

there  will  be  one  or  more  single  pole  switches  in- 
stalled to  control  some  of  the  lights  and  the 
operation  of  installing  them  will  be  next  treated  of. 
The  simple  form  of  single  pole  snap  switch  is  shown 
in  Fig.  33  without  its  cover,  and  may  be  procured 
in  many  finishes  to  suit  the  fixtures,  the  most  used 
finish  for  general  purposes  being  nickel  plate. 

Switch   Wires.     The   running   of   switch   wires 
where   simple   single   pole   switches   are   used   to 


control  a  light  from  only  one  place  as  in  Fig.  34 
is  as  follows: 

At  the  outlet  in  the  ceiling  or  wherever  the  light 
is  to  be  located,  only  one  piece  of  wire  A  is  brought 
down  through  the  hole  from  the  main  circuit  for 
the  fixture. 

Another  piece  of  wire  B  is  cut  long  enough 
to  reach  from  the  fixture  up  through  the  hole, 
fasten  to  the  knob  and  run  clear  along  the  floor 
down  to  the  switch  outlet  with  enough  left  to  make 
connection  to  the  switch. 


56 


WIRING   HOUSES 


A  third  piece  C  is  cut  and  run  from  the  other 
side  of  the  circuit  at  the  outlet,  that  is  from  the 
main  wire  other  than  the  one  to  which  the  outlet 
wire  is  connected.  This  second  piece  also  runs 
clear  down  to  the  switch. 

It  will  be  seen  then  that  the  current  passing  down 


Fig.  U. 


through  the  first  short  piece  A  through  the  fixture 
flows  along  the  second  length  B  through  the  switch 
and  back  to  the  circuit  by  the  wire  C. 


Pulling  down  Switch  Wires.     To  cut  the  loom 
for  the  switch  outlets  measure  the  distance  from 


INSTALLING   LIGHTS  57 

the  switch  outlet  to  the  ceiling  which  should  be  the 
same  for  all  switch  outlets  on  the  first  floor.  Then 
allow  enough  for  the  thickness  of  the  ceiling  or 
beam  under  the  floor,  and  also  be  sure  that  the 
loom  will  reach  in  one  piece  from  the  outlet  to  the 
knob  at  the  point  where  the  switch  wire  leaves 
the  joist  to  run  down  the  wall.  Then  slip  the 
switch  wires  into  the  loom  and  pull  through  the 
ends,  bare  the  copper  for  a  few  inches  and  twist  the 
ends  together  ready  for  attachment  to  the  fish 
line. 

The  switch  outlet  having  been  cut  in  the  wall 
through  the  lath  and  plaster  the  mouse  is  dropped 
down  from  above  pulling  the  string  along  with  it 
all  but  the  loop  end  which  is  tied  tightly  to  the 
twisted  end  of  the  switch  wires. 

A  piece  of  hooked  wire  is  then  run  in  the  outlet 
hole  down-stairs  and  the  fish  line  pulled  through. 
Pulling  on  the  line  soon  brings  out  the  twisted 
ends  of  the  switch  wires,  if  they  stick,  they  must  be 
helped  from  above,  it  is  very  helpful  here  to  have 
an  assistant  who  can  guide  the  wires  down.  The 
twisted  ends  arc  then  loosed  from  the  fish  line  and 
left  for  connection  to  the  switch  later  on. 

Hall  Lights.  It  is  often  very  convenient  to 
locate  a  light  in  a  hallway  for  instance  so  that  by 
means  of  two  switches  it  can  be  controlled  from 
two  places.  A  person  desiring  to  go  down-stairs 
at  night  can  then  light  the  lamp  in  the  down-stairs 
hall  before  descending,   by  means  of  the  switch 


58 


WIRING   HOUSES 


up-stairs;  and  then  after  having  descended  can 
extinguish  the  lamp  from  the  switch  down -stairs. 
Or  it  may  be  lighted  from  down-stairs  and  extin- 


Fig.  35. 


guished  from   up-stairs.     Either  switch  will  light 
or  extinguish  the  lamp. 

The  wiring  for  this  arrangement  is  not   com- 


INSTALLING    LIGHTS  59 

plicated  but  needs  two  special  switches  called 
"  three  way  switches." 

A  diagram  of  the  wiring  is  in  Fig.  35.  The 
rosette  of  the  hall  light  L  is  connected  on  one  side  A 
to  the  circuit  as  shown  and  the  other  side  of  the 
rosette  is  connected  to  the  single  binding  post  on 
the  switch  S  up-stairs.  This  binding  post  is  quite 
easily  distinguished  as  it  is  strapped  to  another 
which  has  no  hole  and  screw  for  a  wire.  The  same 
binding  post  on  the  switch  down-stairs  is  connected 
B  to  the  circuit  but  not  to  the  same  side  of  the  circuit 
as  the  top  switch  rosette  wire.  Then  two  wires 
are  run,  one  between  each  of  the  two  remaining 
binding  posts  of  the  switches  as  shown. 

Where  there  is  an  available  circuit  both  up-stairs 
and  down -stairs  or  the  same  circuits  runs  near  each 
switch  as  shown,  the  wires  may  be  attached  to 
each  taking  care  that  they  go  to  different  sides  of 
the  circuit.  But  where  there  is  no  circuit  down- 
stairs the  lower  switch  wire  must  be  run  upstairs 
and  tapped  on  to  the  same  circuit  as  the  rosette. 

A  study  of  the  illustration  will  make  this  clearer 
than  pages  of  explanation.     It  really  is  very  simple. 

What  happens  is  as  follows:  When  the  button 
of  one  switch  is  turned  it  connects  one  live  wire 
to  one  of  the  two  switch-wires  and  the  current 
flows  along  through  the  second  switch  and  out 
through  the  lamp  to  the  other  live  wire  lighting 
the  lamp.  Now  if  the  second  switch  is  turned,  it 
changes  the  lamp  wire  to  the  other  switch-wire 
and  the  lamp  goes  out. 


CHAPTER  V. 


Other  Methods  of  Wiring. 

Open  Work  or  Cleat  Work.  Where  appearance 
is  no  object  the  wires  may  be  run  on  knobs  or 
held  by  cleats  on  the  ceiling  or  walls  of  the  room. 
In  the  case  of  barns,  outhouses  and  even  in  cellars 
this  class  of  wiring  may  suffice.  But  it  is  not  neat 
and  even  moulding  work  is  better  and  more 
symmetrical. 

The  general  directions  for  open  work  are  not 
much  different  than  for  running  wires  between  the 
floors  except  that  cleats  holding  two  wires  may  be 
used.  The  wire  should  be  rubber  covered  and 
stretched  tight  between  the  knobs  or  cleats.  Wires 
must  be  kept  apart  at  all  times  and  a  generous 
use  of  knobs  or  cleats  is  recommended  to  that  end. 

Where  a  long  run  of  open  work  is  to  be  made, 
the  two  extreme  ends  of  the  circuit  should  be 
stretched  tight  first,  that  is  of  course  on  a  straight 
run  such  as  the  whole  length  of  a  hallway  or  cellar. 
The  end  knobs  or  cleats  being  in  place  it  is  easier 
to  put  up  the  intermediate  ones  straight. 

In  general  wires  should  be  supported  by  cleats 
or  knobs  at  least  at  every  4i  feet  but  often  it  is 
better  to  space  them  closer. 

60 


OTHER    METHODS    OF    WIRING 


61 


This  class  of  work  is  a  little  hard  for  the  be- 
ginner as  the  wires  must  be  stretched  tight  in  order 
to  look  neat.  An  assistant  would  be  of  use  to 
help  stretch  the  wire  and  hold  it  tight  while  it  is 
being  cleated  and  the  screws  driven  home. 

When  the  circuit  turns  at  an  angle  the  wires 
may  be  fastened  as  in  Fig.  36  which  shows  the 
arrangement  of  the  cleats  although  where  the  wire 
is  stiff  enough  the  middle  cleat  may  be  dispensed 


Fig.  36. 


with.  The  cleats  used  are  porcelain  and  come  in 
pairs,  some  being  interchangeable  top  and  bottom. 

This  class  of  work  should  not  be  installed  out- 
doors or  where  it  is  damp.  The  wiring  of  damp 
places  is  best  done  on  knobs,  and  outdoors,  except 
under  cover,  on  glass  insulators. 

Where  money  is  less  an  object  than  time  or 
labor,  loom  may  be  used  throughout  dispensing 
with  knobs  almost  entirely.     Pockets  are  opened 


€2  WIRING   HOUSES 

only  at  the  outlets  and  at  a  few  other  places  such 
as  where  the  wires  run  down  in  the  walls.  The 
wire  then  being  encased  in  loom  for  its  entire 
length  is  pulled  under  the  floors  for  the  entire 
distance  being  left  without  loom  at  the  outlets  for 
a  short  space  in  order  to  make  fast  to  the  knob. 
Knobs  are  used  at  the  outlets  of  course  to  secure 
the  wires  for  the  lights  and  the  switches. 

A  snake  wire  of  steel  is  useful  to  pull  the  loomed 
wires  from  outlet  to  outlet.  This  snake  wire  is  of 
flat  steel  and  one  end  being  bent  to  prevent  it 
catching  in  projections  beneath  the  floor  it  is 
pushed  under  the  floor  boards  and  as  it  reaches 
an  outlet  the  wires  made  fast  at  its  other  end  are 
pulled  along  by  its  aid. 

In  some  types  of  house  construction  there  will 
be  found  a  space  between  the  joists  and  the  plaster 
allowing  the  wires  to  be  fished  without  boring  the 
joists.  Otherwise  the  joists  must  be  bored  and 
tubed  as  usual. 

Wiring  in  Wooden  Moulding.  In  buildings 
where  it  is  not  desired  to  wire  on  the  plans  de- 
scribed the  wires  are  run  in  wooden  moulding 
fastened  to  the  ceilings  or  to  the  walls.  This 
moulding  consists  of  two  parts,  the  backing  which  is 
a  flat  strip  having  grooves  cut  in  it  for  the  wires  to 
lie  in,  and  the  capping,  a  thin  lath  which  is  nailed 
over  the  wires  to  hold  them  in  place  and  to  conceal 
them. 

This  moulding  should  be  painted  with  a  moisture 


OTHER   METHODS    OF   WIRING  63 

repelling  paint  inside  and  out  and  the  wire  used 
must  be  rubber  covered. 

Under  no  circumstances  should  this  moulding  be 
used  outdoors  or  in  damp  places. 

In  wiring  with  moulding,  the  backing  is  first 
nailed  in  place,  the  wire  laid  in  the  grooves  and 
held  temporarily  in  place  by  brads  which  are 
removed  when  the  capping  is  nailed  on.  It  is 
better  to  use  screws  instead  of  nails  to  fasten  the 
capping  as  it  may  then  be  the  easier  removed  when 
necessary.  Whether  nails  or  screws  be  used,  they 
are  to  be  driven  through  the  central  rib  of  the  back- 
ing and  not  through  the  bottom  of  the  grooves. 
It  is  best  to  plan  so  that  there  are  no  splices 
in  the  wires,  but  have  them  continuous  through- 
out. 

When  taps  are  necessary  they  may  be  made  as 
usual,  by  twisting  the  tap  wires  on  and  soldering 
them  but  a  better  plan  is  to  use  one  of  the  tap 
devices  described  later  on. 

When  the  circuit  turns  at  an  angle,  the  moulding 
should  be  neatly  cut  and  mitred  as  in  a  picture 
frame.  This  class  of  work  is  one  where  the  me- 
chanical skill  of  the  operator  becomes  apparent 
as  it  is  really  joiners  work  and  the  neat  fitting  of 
the  pieces  in  their  place  and  the  straightness  with 
which  the  moulding  is  run  are  very  noticeable. 
A  great  amount  of  ingenuity  and  taste  may  be 
displayed  in  the  manner  with  which  the  work  is 
done  and  a  job  of  moulding  may  be  either  an 
eyesore   or   an  ornament.     Sometimes   it   is   nice 


64 


WIRING    HOUSES 


to  continue  the  moulding  beyond  where  the  wires 
stop  in  order  to  gain  symmetry  of  design. 

Although  it  is  often  quicker  to  use  moulding  all 
the  way,  switch  wires  may  be  often  pulled  down 
inside  the  walls  in  loom  and  out  at  the  switch  outlet. 

Moulding  Taps.  Where  a  tap  is  to  be  taken 
off  a  run  of  moulding  one  of  the  tap  wires  will 


naturally  cross  the  main  wires  and  the  moulding. 
The  crossing  tap  wire  is  led  out  through  a  slot  cut 
in  the  main  wire  moulding  capping  and  crosses 
outside  this  capping  which  is  thus  interposed 
between  the  wires  and  keeps  them  apart.  The 
other  tap  wire  is  led  out  of  a  slot  cut  in  the  outside 
wall  of  the  main  moulding  and  into  the  groove  of 
the  tap  moulding. 


OTHER    METHODS   OF   WIRING  65 

A  neater  and  better  plan  is  to  use  the  tap  device 
shown  in  Fig.  37  which  is  made  by  the  H.  T. 
Paiste  Co.  of  Philadelphia.  It  can  be  bought  at 
almost  any  electrical  supply  store  and  is  simple 
in  attachment  the  illustration  showing  sufficiently 
well  its  application. 

Where  two  circuits  have  to  cross  each  other,  a 
cross  over  device  made  by  the  same  company  is 
used  as  illustrated  in  Fig.  38. 


Fig.  38. 

The  moulding  of  the  crossing  wires  is  butted  up 
to  the  main  run  of  moulding,  a  piece  of  capping  cut 
from  the  latter  and  the  device  installed  as  in  the 
illustration.  This  interposes  a  solid  base  of  porce- 
lain between  the  two  circuits. 

Wall  Moulding  Method.  One  of  the  slowest  and 
hardest  jobs  in  wiring  houses  is  the  boring  of  in- 


66  WIRING    HOUSES 

numerable  holes  through  the  floor  joists  to  ac- 
commodate the  circuit  wires  which  run  through 
them.  In  a  house  of  six  or  eight  rooms  there  may 
easily  be  a  hundred  of  these  holes  and  the  boring 
of  a  hundred  j^  inch  holes  through  floor  joists  with 
a  brace  and  bit  is  no  light  task.  Then  the  tubes 
must  be  inserted  and  the  wires  pulled  through  all 
of  which  may  be  saved  if  the  operator  is  skillful 
and  there  is  no  objection  to  moulding  on  the  side 
walls.  This  moulding  may  be  of  a  special  kind 
resembling  picture  moulding  or  it  may  be  the 
regular  electric  wire  wooden  moulding  as  de- 
sired. 

In  this  side  wall  moulding  method  the  wires  that 
otherwise  would  run  through  the  holes  in  the  joists 
up-stairs  are  run  in  moulding  on  the  side  walls 
down-stairs. 

For  example  the  main  circuit  that  would  run 
from  the  front  of  a  house  to  the  rear  necessitating 
boring  and  tubing  the  whole  distance  may  be  run 
in  moulding  on  the  wall  of  the  room  below  as  shown 
by  the  heavy  dotted  line  in  Fig.  39.  It  may  not 
run  as  straight  as  by  the  other  plan  but  will  only 
require  a  few  feet  more  wire. 

Taps  for  ceiling  outlets  H,  K,  D,  L  and  M  are 
taken  off  and  fished  up-stairs  in  loom  then  run  as 
usual  between  the  joists. 

The  number  of  pockets  is  also  very  much  re- 
duced and  it  is  probable  that  there  will  be  no  need 
to  take  up  an  entire  board  anywhere. 

The  outlet  at  G  can  be  run  in  moulding  on  the 


OTHER    METHODS    CF   WIRING 


67 


ceiling  being  fed  by  wires  coming  through  tubed 
holes  in  the  wall  of  the  next  room. 

Where  no  picture  moulding  has  been  installed 
this  special  moulding  or  the  regular  kind  is  run 


Fig.  39. 


about  10  or  12  inches  below  the  ceiling  or  to  suit 
personal  taste  and  the  wall  paper  border. 

As  in  the  case  of  kitchen  outlet  G  at  partitions 
between  two  rooms  the  partition  wall  is  bored  and 


68 


WIRING   HOUSES 


the  wires  pulled  through  in  loom  or  tubes  then  con- 
tinued on  to  the  end  of  the  circuit. 

The  ends  for  attachment  to  the  cut-out  box  down- 


Fig.  40. 


stairs  or  to  the  main  switch  are  encased  in  loom  and 
pulled  up  or  down  inside  the  walls,  according  as  the 
service  is  up-stairs  or  down-stairs. 


OTHER   METHODS   OF   WIRING  69 

Taps  running  to  ceiling  outlets  are  to  be  run  be- 
tween the  joists  to  a  point  as  nearly  above  the 
moulding  as  possible  then  holes  being  bored  through 
both  moulding  and  wall  the  ends  of  these  taps  may 
be  fished  down  and  through  them  and  soldered 
on  to  the  wire  in  the  moulding. 

In  the  case  of  the  live  wire  running  from  the 
main  wires  to  a  switch,  this  is  easily  pulled  down 
to  the  outlet  from  a  point  in  the  moulding  directly 
above  it.  Of  course  it  should  be  loomed  first. 
This  makes  a  shorter  run  than  in  the  ordinary 
method  as  the  switch  live  wire  may  be  taken  from 
a  near  point  right  above  it  perhaps,  whereas  in  the 
other  method  it  has  to  run  generally  clear  to  the 
ceiling  outlet.  The  wiring  of  a  switch  is  clearly 
shown  in  Fig.  40  where  R  is  the  rosette,  M 
the  wall  moulding  and  5  the  switch  on  the 
wall. 

There  is  no  practical  difficulty  about  this  system 
of  wiring  except  that  incurred  by  the  appearance 
of  the  moulding  or  on  account  of  the  down-stairs 
wall  running  irregularly.  It  puts  the  wires 
where  they  may  be  tapped  on  for  additional 
lights  or  wall  brackets  in  a  more  accessible  posi- 
tion. 

Outdoor  Service.  When  the  battery  is  to  be 
located  in  a  separate  building  the  wires  leading  to 
the  house  from  the  battery  switchboard  must  be 
properly  put  up  so  as  to  withstand  all  weather 
conditions. 


70  WIRING    HOUSES 

In  the  first  case  the  wire  must  be  weatherproof, 
triple  braid  the  weights  and  sizes  being  given  in 
Table  1.  Sizes  larger  than  No.  12  B.  &  S.  should 
be  stranded  as  they  are  then  easier  to  handle  and 
less  liable  to  fracture  when  bent. 

The  insulators  will  be  of  glass  and  mounted  on 
pins  or  brackets  of  wood  or  iron  as  may  be  decided- 
Porcelain  knobs  should  not  be  used  to  carry 
main  wires  where  they  will  be  exposed  to  rain  or 
snow.  In  fact  it  is  better  to  use  glass  insulators 
exclusively  outdoors  except  of  course  where 
running  a  line  for  a  light  on  the  porch  or  inasimilar 
case. 

Before  running  an  outdoor  line,  the  route 
should  be  first  surveyed.  It  should  be  run  in  as 
straight  a  direction  to  economize  wire  and  must 
be  supported  at  frequent  intervals  to  allow  for 
the  weight  of  snow  which  accumulates  on  wires 
in  the  winter,  and  for  the  strain  of  heavy  winds. 
In  running  long  outdoor  lines  it  is  customary  to 
allow  at  least  a  pole  at  each  125  feet  but  in  the 
present  ease  it  will  be  better  to  keep  well  within 
this  distance. 

Although  the  wire  itself  may  be  exposed  to  the 
weather  when  properly  supported  on  insulators, 
it  is  necessary  to  guard  against  rain  running  along 
it  and  entering  the  house  by  way  of  the  entrance 
holes.  This  not  only  would  damage  the  wall  but 
would  seriously  endanger  the  insulation  at  the 
point  of  entrance.  This  contingency  is  guarded 
against  by  fastening  the  wires  below  the  entrance 


^^M^^^^ 


Fig.  41. 


72  WIRING   HOUSES 

holes,  giving  them  a  loop  from  which  the  water  can 
drip  or  by  a  combination  of  both. 

The  entrance  holes  must  be  bushed  with  porce- 
lain tubes  which  are  made  for  this  purpose  with  a 
curve,  which  curve  is  to  be  turned  downwards. 

In  regular  110  volt  work,  an  iron  pipe  about 
10  feet  long  is  bent  at  its  lower  end  so  that  it  will 
enter  the  cellar,  equipped  with  a  proper  bushing  at 
the  top  and  the  wires  pulled  through.  After  this 
it  is  fastened  up  upright  against  the  outside  wall. 
Fig.  41.  Two  insulators  on  iron  brackets  are  lo- 
cated at  each  side  of  the  pipe  at  the  top  which 
should  be  at  least  10  feet  from  the  ground  de- 
pending upon  whether  wagons  are  liable  to  pass 
near  it  and  the  angle  with  which  the  wires  come 
down  to  enter  it.  The  service  wires  leading  from 
the  battery  or  plant  being  then  fastened  to  the 
insulators  may  be  led  in  to  the  cut-out  box  or 
service  switch. 

It  is  generally  easier  to  make  up  the  pipe  with 
two  wires  long  enough  to  reach  from  the  service 
switch  up  the  pipe  and  leave  enough  free  ends  to 
connect  to  the  wires  coming  from  the  plant. 

Where  suitable  bushings  are  not  used  to  close 
the  end  of  the  pipe  outdoors,  it  should  be  filled 
with  tape  and  a  few  wooden  wedges  driven  in  to 
keep  out  dampness.  The  wires,  however,  must  be 
guarded  against  any  possible  cutting  on  the  edges 
of  the  pipe.  Bushings  such  as  described  are 
cheaper  in  the  long  run. 

Where  the  wires  come  down  from  a  pole  set  back 


74 


WIRING  HOUSES 


of  the  'house,  one  insulator  will  be  mounted  above 
the  other  so  as  to  keep  the  wires  apart  as  in  Fig.  42, 
Where  the  service  wires  come  in  up-stairs  in  the 
attic  for  example  the  pipe  is  dispensed  with  and 
insulators  and  tubes  used.  This  method  requires 
the  use  of  a  ladder  unless  the  entrance  can  be 
located  near  a  window. 


Fig.  43. — How  to  tie  a  wire  onto  a  glass  insulator. 


Fig.  44. — 'Dead  ending  a  wire  on  a  glass  insulator  and  iron 
bracket — showing  drip  loop  and  inclined  porcelain  tube. 


CHAPTER  VI. 


Notes  on  Materials. 

Estimating  the  Material  Required.  To  estimate 
the  material  required  a  careful  survey  must  be 
made  of  the  job  after  having  digested  the  wiring 
directions  already  given. 

The  number  of  porcelain  tubes  will  depend  upon 
the  number  of  joists  and  the  wires  running  through 
them  to  which  is  to  be  added  about  25%  for  use  in 
odd  places.  Often  from  150  to  200  will  be  re- 
quired in  a  frame  house  of  7  or  8  rooms  wired  on 
the  concealed  knob  and  tube  plan. 

Knobs  may  be  estimated  at  about  1  to  each  3  feet 
of  wire  needed  which  allowance  should  be  sufficient 
for  most  jobs. 

The  wire  itself  may  be  figured  by  measuring  the 
route  to  be  followed  but  a  generous  allowance 
should  be  made  for  ties  or  twisting  around  the  knobs 
and  also  for  the  irregular  manner  in  which  it  will 
run  through  the  tubes  in  the  joists.  As  wire  is 
useful  to  have  on  hand  allow  50%  more  than  the 
estimate.  This  applies  to  small  jobs,  large  jobs 
may  be  calculated  to  close  figures  and  the  wire 
bought  in  stock  coils. 

Flexible   conduit   or  loom   being  somewhat  ex 

75 


76  WIRING  HOUSES 

pensive  can  be  estimated  somewhat  closer  if  suffi- 
cient measurements  are  made.  There  will  be  two 
lengths  for  each  single  pole  switch  reaching  from 
the  switch  to  the  space  between  the  floor  joists. 
This  will  average  12  feet  per  switch  in  rooms  of 
ordinary  height.  For  ceiling  outlets  short  pieces 
a  foot  or  less  in  length  will  suffice.  From  the  cir- 
cuit up-stairs  to  the  cellar  ceiling  (or  the  attic  floor) 
in  the  case  of  the  service  will  be  easy  of  measure- 
ment. 

A  roll  of  friction  tape  and  one  of  rubber  tape 
will  be  sufficient  for  quite  a  large  job. 

Other  supplies  such  as  nails  or  screws  will  be 
easy  to  figure. 

Material  Required  in  Wiring.  No.  5  porcelain 
knobs  for  No .  12  or  No.  14  wire  have  a  groove  ^  inch 
wide  to  hold  the  wire,  measure  1|  inch  from  the 
top  to  the  surface  upon  which  the  insulator  is 
fastened  and  have  a  \  inch  hole  for  the  nail  or 
screw.  No.  5|  porcelain  knobs  are  similar  except 
that  they  hold  the  wire  higher  from  the  surface 
wired  over  being  \%  inches  high. 

Porcelain  tubes  should  be  unglazed  and  will  vary 
in  length  according  to  circumstances.  But  in 
general  for  floor  joists  and  most  other  woodwork  in 
the  house  they  may  be  3  to  4  inches  long  measuring 
under  the  head.  For  places  where  two  joists  come 
together  they  should  be  probably  6  inches  long. 
The  inside  diameter  for  wires  not  larger  than 
No.  12  B.  &  S.  should  be  ^  inch  and  the  outside 


NOTES   ON   MATERIALS  77 

diameter  %  inch.  A  tube  f  inch  inside  and  %  inch 
outside  is  preferable  for  No.  12  B.  &  S.  wire,  as 
it  will  be  easier  to  pull  through  a  lot  of  tubes  when 
in  the  joists. 

Split  Knobs.  Split  knobs  are  porcelain  insula- 
tors made  in  two  pieces  the  wire  being  held  tightly 
between  the  upper  and  lower  portions  when  the 
screw  through  the  center  of  the  knob  is  tightened. 
Nails  and  nail  heads  should  not  be  used  with  split 
knobs.  For  the  latter  reason  it  is  very  hard  work 
to  use  split  knobs  under  a  floor  and  in  similar 
places  as  there  is  not  often  enough  room  to  handle 
a  screw  driver.  Moreover  there  is  a  greater  lia- 
bility for  one  inexpert  to  insufficiently  tighten  the 
screw  and  the  wire  will  be  loose.  And  the  breakage 
is  liable  to  be  greater. 

In  the  solid  knob  method  if  the  knob  is  not  abo- 
lutely  immovable  on  the  joist  it  will  at  any  rate 
hold  the  wire  as  the  latter  is  not  dependent  upon 
the  centre  nail  or  screw.  But  with  split  knobs  the 
screw  has  to  perform  the  double  function  of  holding 
the  wire  and  holding  the  knob. 

For  wiring  in  exposed  places  where  the  screw 
driver  can  be  used  readily,  split  knobs  are  prefer- 
able as  they  make  a  neat  job  and  the  screw 
being  the  easier  driven  allows  no  excuse  for  loose 
wires. 

Screws  and  Nails.  Screws  for  switches  and 
rosettes  will  be  generally  Flat  Head  Bright  wood 


78  WIRING   HOUSES 

screws,  No.  6  and  from  1  inch  to  2  inches  in 
length,  according  to  whether  they  are  to  be  used  in 
ceiling  boards  or  only  in  lath  and  plaster. 

Where  screws  are  used  for  the  knobs  they  should 
be  also  Flat  Head  Bright  wood  screws.  For  No.  5 
and  No.  5h,  If  inch  and  2  inch  No.  8  are  suitable 
although  2  and  2\  give  a  firmer  hold. 

Wire  nails  are  suitable  for  knobs,  using  nail 
heads  as  mentioned  before. 

Screws  and  not  nails  are  needed  where  wooden 
moulding  is  run  on  plaster  ceilings  as  nails  will 
not  hold. 

Moulding.  The  wooden  moulding  ordinarily 
used  in  wiring  is  made  of  hard  wood  and  painted 
with  moisture  repelling  paint  or  varnish.  The 
back  as  well  as  the  grooves  should  be  painted  or 
varnished  and  the  whole  outside  may  be  painted 
any  desired  color  after  being  installed  on  the  wall 
or  ceiling. 

The  size  for  No.  12  to  No.  14  wire  is  No.  A-2 
and  has  grooves  J2  inch  wide.  For  Nos.  8  and  10 
wire  the  size  is  No.  B-l  with  grooves  -fa  inch  wide. 
The  size  of  the  grooves  should  be  specified  in  order- 
ing special  mouldings  or  the  number  of  the  wire 
given. 

Bits.  Bits  used  in  boring  holes  for  tubes  or 
outlets  will  of  course  follow  the  size  of  the  hole 
desired.  If  neat  holes  are  desired  use  double  cutter 
bits,  if  a  lot  of  holes  are  needed  such  as  under  the 


NOTES    ON   MATERIALS  79 

floor  and  through  the  joists  the  work  is  much  easier 
with  single  cutter  bits  such  as  the  Ford  bit. 

Tubes  really  should  fit  tight  but  it  is  the  general 
rule  to  use  a  bit  a  trifle  larger  than  the  tube  and 
depend  upon  the  fact  that  there  is  no  motion  to  the 
wire  to  make  the  tube  stay  in  place.  For  a  loose 
fit  use  an  l}&  inch  bit  for  tubes  with  an  outside 
diameter  of  %  inch  and  a  %  inch  bit  for  tubes  with 
an  outside  diameter  of  %.  The  rl  inch  bit  will 
also  be  suitable  for  the  outlets  and  the  x/i  inch  loom. 

In  locating  the  first  holes  in  the  ceiling  for 
marking  outlets  a  \  inch  Syracuse  bit  is  best,  and 
may  be  as  long  as  convenient  one  18  inches  long 
being  most  generally  useful. 

Tape.  The  real  insulating  tape  is  a  rubber 
compound  and  must  be  put  on  with  heat.  It  is 
best  applied  immediately  after  soldering  a  joint 
when  it  will  adhere  best  but  the  joint  may  of 
course  be  heated  later  on  and  the  tape  applied. 
This  rubber  tape  should  not  be  confounded  with 
the  sticky  or  friction  tapes.  These  are  used  merely 
to  cover  the  rubber  tape  and  protect  it  although 
often  wrongly  used  for  insulation. 

The  insulation  at  a  joint  should  be  at  least  as  good 
as  that  on  the  wire  itself. 

Taped  joints  outdoors  should  be  painted  with 
P.  &  B.  paint  which  is  a  rubber  compound  and  not 
an  asphaltum  mixture.  Failing  genuine  P.  &  B. 
a  good  grade  of  asphaltum  paint  is  better  than 
nothing. 


80  WIRING   HOUSES 


TABLE    1. 
Copper  Wire  Properties. 

Weatherproof  insulation       Rubber 


No. 

Lbs.  per 

Carrying 

insulation: 

B.  &  S. 

Circular 

thousand 

capacity 

Carrying 

gauge 

mils 

feet 

amperes 

capacity 

00 

133,325 

522 

220 

150 

0 

105,625 

425 

185 

127 

1 

83,694 

328 

156 

107 

2 

66,373 

270 

131 

90 

4 

41,742 

170 

92 

65 

6 

26,250 

115 

65 

46 

8 

16,509 

78 

46 

33 

10 

10,381 

53 

32 

24 

12 

6,530 

35 

23 

17 

14 

4,107 

25 

16 

12 

16 

2,583 

16 

8 

6 

18 

1,624 

12 

5 

3 

Figuring  the  Size  of  Wire.  The  size  of  wire  used 
depends  upon  the  amount  of  current  to  be  carried 
and  the  distance  it  will  travel. 

Although  a  good  conductor  of  electricity,  copper 
presents  some  resistance.  A  wire  that  would  carry 
5  amperes  without  loss  would  not  be  suitable  for  10 
amperes  if  both  currents  were  to  travel  the  same  dis- 
tance. The  results  of  resistance  will  be  shown  in  a 
dimming  of  the  lights.  Moreover,  if  the  wire  be  too 
small  for  the  current  carried  it  will  get  dangerously 
hot.  Fuses  will  be  used  to  take  care  of  this  excess- 
current  when  it  arises  from  a  short  circuit  but  for 
normal  conditions  the  wire  should  be  figured  large 
enough. 


NOTES   ON   MATERIALS  81 

The  safe  carrying  capacity  of  copper  wire  is 
shown  in  the  Table  I.  The  lower  limits  for  rubber 
covered  wire  is  due  to  the  fact  that  such  wire  is 
generally  used  enclosed  where  the  heating  would 
be  more  pronounced  and  also  because  rubber 
deteriorates  more  than  the  weatherproof  wire 
insulation  on  being  heated. 

Although  the  carrying  capacity  will  determine 
the  safe  size  of  the  wire,  it  will  not  ensure  its  being 
large  enough  to  carry  the  current  without  a  loss. 
In  low  voltage  lighting  this  loss  must  be  con- 
sidered, as  for  example  a  loss  of  3  volts  would  be 
worse  on  a  circuit  of  30  volts  and  affect  the  lights 
more  than  would  the  same  loss  on  a  wire  where  the 
voltage  was   110,  being  a  greater  proportion. 

The  resistance  of  a  foot  of  copper  wire  one  cir- 
cular mil  or  one  circular  thousandth  of  an  inch 
in  area  is  about  11  ohms. 

It  is  a  fundamental  rule  of  electricity  that  the 
voltage  expended  in  carrying  a  given  current  a 
given  distance  depends  upon  the  resistance  in  the 
circuit.  It  would  actually  need  an  expenditure  of 
11  volts  to  cause  one  ampere  to  pass  through  this 
circular  mil  foot  of  wire.  Therefore  supposing  the 
voltage  of  the  plant  was  30,  there  would  only  be 
19  volts  left  for  the  lamp. 

Of  course  a  wire  so  small  would  never  be  used, 
it  would  burn  up  with  the  current  but  it  is  used  as 
an  illustration. 

In  order  therefore  to  have  the  wire  of  the  right 
area  it  must  have  the  proper  number  of  circular 


82  WIRING    HOUSES 

mils  which  is  determined  by  a  simple  calculation. 
Referring  to  Table  I  No.  12  B.  &  S.  has  an  area  of 
6530  circular  mils  so  it  is  clear  that  a  foot  of  this 
would  only  expend  1/6530  of  the  11  volts  for  the 
same  one  ampere  for  its  area  having  been  in- 
creased would  have  correspondingly  reduced  the 
resistance. 

Applying  these  facts  to  a  simple  arithmetical 
formula  gives  a  rule  to  calculate  the  size  of  wire 
for  any  current  and  any  distance. 

Take  the  entire  length  of  the  wire,  both  sides  of 
the  circuit  L.  Multiply  this  in  feet  by  the  am- 
peres A  to  be  carried  and  then  multiply  the  result 
by  11,  or  the  ohms  in  a  mil  foot  of  copper  wire. 
The  answer  will  give  the  size  of  wire  in  circular 
mils  to  carry  the  current  the  required  distance,  and 
a  reference  to  Table  I  will  show  the  numerical 
size  of  wire  needed.  This  allows  a  lose  of  one  volt. 
If  more  or  less  loss  is  allowed  divide  the  above 
answer  by  the  loss  allowable. 

For  example,  suppose  10  amperes  is  to  be 
carried  200  feet  and  one  volt  loss  allowed.  Then 
the  entire  wire  length  will  be  400  feet  and  400  times 
10  times  11  equals  44,000  circular  mils.  The 
nearest  size  of  wire  in  the  table  is  No.  4  B.  &  S. 
with  41,742. 

Another  example,  12  amperes  a  distance  of 
240  feet  with  a  loss  of  2  volts.  In  this  case  perhaps 
the  voltage  at  the  battery  in  a  distant  building 
is  32,  and  30  is  required  at  the  lamps.  Then  the 
entire  wire  length  will  be  480  feet  and  the  multi- 


NOTES  ON    MATERIALS  83 

plying  together  of  12,480  and  11  equals  63,360. 
This  divided  by  2  equals  31,680.  The  nearest 
in  the  table  is  again  No.  4.  A  number  5  wire  is 
made,  but  the  extra  area  is  an  advantage. 

As  a  formula  the  rule  would  be  stated  as  follows. 

LXAX11         ,..,., 

— : =  Area  in  circular  mils. 

volts    loss 

These  rules  apply  to  all  voltages.  For  example,  in 
the  last  calculation,  the  loss  would  be  2  volts,  whe- 
ther the  line  voltage  was  32,110,  or  even  220  volts. 
But  the  percentage  would  of  course  be  different, 
and  therefore  the  effect  on  the  light  would  vary. 
A  loss  of  2  volts  in  32,  would  be  worse  than  a  loss 
of  2  volts  in  a  circuit  of  110  volts. 

The  formula  gives  the  actual  volts  loss  for  a  given 
number  of  amperes,  a  given  distance  and  a  wire  of 
a  given  diameter.  It  is  evident  that  with  a  higher 
voltage  the  current  through  the  same  resistance 
would  be  greater,  but  increasing  the  current  in  the 
wire  would  naturally  increase  the  figure  correspond- 
ing to  the  amperes  in  the  formula. 

Where  it  is  desired  to  get  the  loss  in  a  given  size 
of  wire,  substitute  the  circular  mils  for  the  loss  in 
the  formula. 

LXAXH 

— ~7^\r —  Loss  in  volts. 

Example,  find  the  loss  in  a  wire  31,680  circular 
mils,  carrying  12  amperes  a  distance  of  240  feet 
single  wire,  or  480  feet  actual.  Then  480  multi- 
plied by  12  multiplied  by  11  equals  63,360.  This 
divided  by  the  circular  mils,  or  31,680  equals  2  volts. 


CHAPTER  VII. 


Conduit  or  Protected  Wiring. 

The  safest  and  most  substantial  methods  of 
wiring  are  those  in  which  the  conductors  are  pro- 
tected by  metal  tape  (armored  cable),  enclosed 
in  iron  pipe  (conduit),  and  which  make  use  of 
iron  boxes  to  enclose  all  joints,  switches  or  re- 
ceptacles. 

It  is  no  more  difficult  to  install  these  systems 
of  wiring  than  to  install  the  open  work  or  knob 
and  tube  systems  described  previously.  In  fact 
in  many  ways  it  is  easier.  The  first  cost  is  greater 
and  the  cutting  and  threading  of  soft  iron  pipe 
or  the  cutting  of  the  armored  cables  perhaps  re- 
quires more  physical  labor.  The  pipe  or  the 
armored  cable  however  may  be  laid  with  less 
labor  and  in  shorter  time,  thus  restoring  the  bal- 
ance. 

There  exists  no  doubt  of  the  greater  safety  and 
general  superiority  of  iron  pipe  or  armored  con- 
duit wiring  systems  over  knob  and  tube  work. 

They  are  as  fireproof  and  damage-proof  as  any 
system  can  be. 

84 


CONDUIT  OR  PROTECTED   WIRING  85 

Armored  Cables.  There  are  several  makes  of 
armored  cables  on  the  market,  sold  under  the 
trade  names  of  "Flex  Steel" — BX,  etc.  All  the 
illustrations  here  are  of  work  done  with  BX. 

In  the  BX  flexible  steel  armored  cable,  the  wire 
conductors  are  insulated  separately  and  then  the 
two  insulated  conductors  are  held  together  by 
further  insulation. 

Outside  of  these  insulated  conductors  is  wound 
spirally,  a  convex  and  a  concave  shaped  metal 
strip,  hot  galvanized  with  zinc,  and  also  a  strip 
of  moisture  repelling  material  laid  between  the 
metal  strips  so  as  to  keep  out  all  moisture. 

BX  may  be  had  with  one,  two,  or  three  con- 
ductors and  in  all  the  usual  wire  sizes. 

These  armored  cables  may  be  run  practically 
anywhere  except  of  course  under  water  or  where 
they  would  be  subjected  to  the  continuous  action 
of  excessive  dampness  or  chemical  fumes.  Where 
likely  to  be  exposed  to  moisture  a  lead  covering 
is  placed  between  the  outer  braid  of  the  con- 
ductors and  the  armor. 

The  main  requirements  as  laid  down  in  the 
National  Electrical  Code  of  the  National  Board 
of  Fire  Underwriters  require : 

(a-)  That  the  cable  be  continuous  from  out- 
let to  outlet — which  means  that  where- 
ever  a  splice  becomes  necessary  it  is 
to  be  made  in  an  approved  metal  box. 


86  WIRING    HOUSES 

(b)  That  the  armor  of  the  cable  must  prop- 

erly enter  and  be  secured  to  all  fittings, 
which  is  done  by  clamps  elsewhere 
shown. 

(c)  That  the  cable  be  mechanically  secured 

in  position,  usually  done  by  means  of 
metal  pipe  straps. 

The  code  also  requires  that  the  metal  armor  be 
permanently  and  effectually  grounded  to  water 
piping,  or  to  other  suitable  ground  connection. 

The  entire  conduit  or  armored  cable  constitut- 
ing the  wiring  system  of  one  building  must  have 
its  iron  pipe  or  armor  effectually  grounded.  This 
is  usually  done  by  seeing  that  good  connection 
is  made  at  all  breaks  in  the  lines,  such  as  at  junc- 
tion or  switch  boxes,  and  that  a  ground  wire 
clamp  is  properly  secured  to  the  conduit  and  to 
an  adjacent  water  pipe. 

W  here  a  gas  pipe  is  used,  the  ground  connec- 
tion must  be  on  the  street  side  of  the  meter. 

Where  there  is  no  gas  or  water  pipe,  an  arti- 
ficial ground  is  made  consisting  of  a  sheet  of  cop- 
per with  a  copper  wire  soldered  to  it,  and  buried 
in  the  ground  where  there  is  continuous  moisture. 

The  idea  is  that  there  shall  be  a  first  class  path 
along  the  armor  into  the  earth  for  any  electricity 
that  hits  the  armor.  It  is  self  evident  then  that 
rusty  joints,  poorly  made  connections  and  even 
only  one  break  in  the  continuity  of  the  ground 
connection  will  utterly  destroy  the  value. 


Malleable  Iron  Panel  Box  Connector. 


^^'*#iKiW!*S»&**-  giBHiy.* 


Combination   Coupling  Joining  Flexible   Conduit   to 
Rigid  Conduit.  -~ 


Stamped  Steel  Panel  Box  Connector  and  Locknut 
on  BX. 


\  \        :r~~f*       ^^5^'^--- 


^BLkAfl. 


Sprague  BX  Steel  Armored  Conductors. 


Showing  How  Panel  Box  Connectors  are  Used  with 
BX  and  Rigid  Conduit.     Also  Two  Multilets. 


PLATE  V. 


88  WIRING    HOUSES 

Although  it  may  be  true  that  where  the  voltage 
is  low,  as  in  the  low  voltage  home  lighting  plants, 
there  is  less  danger  than  where  it  is  higher,  it  is 
better  to  wire  as  if  for  110  volts  even  if  32  are 
only  going  to  be  used. 

Good  wiring  is  good  insurance  in  itself. 

Installing  Armored  Cables.  The  actual  in- 
stalling of  BX  or  other  cable  is  by  no  means 
complicated.  It  may  be  pulled  under  the  floors 
or  clown  in  the  walls  wherever  desired. 

The  securing  of  the  BX  to  the  joists  or  beams 
is  done  with  pipe  straps  which  may  be  nailed 
or  screwed  fast,  gripping  the  cable  so  that  it 
cannot  shift.  In  no  case  is  the  strain  of  a  wire 
or  cable  to  come  directly  upon  a  screw  terminal, 
such  as  in  a  socket  or  on  a  switch.  The  cable  is 
always  made  fast  before  the  wires  are  connected. 

At  all  places  where  a  tap,  joint  or  splice  is  to 
be  made  or  a  switch,  socket  or  receptacle  is  to  be 
attached,  an  approved  iron  box  must  be  used. 
This  is  to  still  farther  carry  out  the  idea  of  pro- 
tecting the  appliances  against  breakage  and  pre- 
venting accidental  contact  with  bare  metal  carry- 
ing current.  Examples  of  details  are  shown  in 
the  illustrations. 

The  end  of  the  BX  is  stripped  of  its  armor  and 
the  two  inside  wires  separated  (but  not  bared  of 
their  own  insulation)  for  6  inches  or  so  dependent 
upon  the  distance  between  where  they  enter  the 
box  and  the  connection  screw. 


CONDUIT  OK  PROTECTED   WIRING 


89 


In  cutting  BX  and  all  similar  armored  wires, 
the  saw  cuts  must  be  made  across  the  metal  tape 
as  shown  in  the  second  figure,  never  in  a  groove 
as  in  the  first  figure.  Otherwise,  the  saw  will 
jam  and  break.  Care  must  always  be  taken  not 
to  saw  beyond  the  metal  tapes  and  into  the  in- 
sulation. A  little  practice  will  help.  Having 
sawed  the  first  metal  tape,  it  may  be  bent  back 
and  broken  off  with  the  pliers  and  the  second 
tape  also  removed.  Then,  the  braid  and  insula- 
tion protecting  the  two  inside  insulated  wires  are 


Wrong  way  to  cut  Right  wav  to  cut 

BX  cable.  BX  cable. 

FIG.  45. 

cut  away.  Do  not  cut  off  any  of  the  insulation  of 
the  two  inside  wires  until  finally  making  the  con- 
nection or  splice. 

There  are  cutting  tools  made  for  stripping 
armored  cable,  which  are  a  great  help. 

The  end  being  now  ready,  a  malleable  iron 
panel  box  connector  is  slipped  over  the  armor 
(the  free  ends  of  the  cable  projecting  from  the 
threaded  end),  and  the  clamp  collar  tightened. 
The  threaded   end   is   now  thrust  through   one  of 


90  WIRING    HOUSES 

the  holes  in  the  iron  box  and  a  lock  nut  screwed 
on  to  draw  the  connector  up  tight. 

This  is  where  a  sheet  iron  box  is  used,  having' 
discs  of  metal  or  knockouts  closing  the  holes 
around  the  box  sides.  These  knockouts  are  driven 
out  by  a  hammer  blow  wherever  entrance  is  de- 
sired. 

Cast  iron  boxes  or  condulets  have  threaded 
nipples,  in  which  case  the  threaded  end  of  the 
panel  box  connector  is  screwed  in  tight  first,  and 
then  the  wire  and  armor  are  inserted  and  clamped. 

The  clamping  of  the  armor  in  this  manner  not 
only  secures  it,  but  by  making  a  good  connection 
between  the  iron  armor  and  the  iron  box,  insures 
that  the  ground  circuit  will  be  unbroken  at  that 
point. 

These  operations  are  really  not  complicated. 
A  study  of  the  illustrations  and,  wherever  pos- 
sible, a  look  at  some  actual  armored  cable  wiring 
will  give  the  instruction  necessary. 

Conduit  Wiring  in  Pipe.  Iron  pipe  or"  rigid 
conduit  work  is  the  safest  form  of  wiring  in  that 
when  properly  installed,  the  wire  is  protected  by 
a  rigid  iron  pipe  against  moisture,  gases  and 
mechanical  injury.  The  iron  pipe  or  conduit  is 
coated  either  with  black  varnish  or  in  the  more 
modern  forms  by  a  coating  of  zinc.  Either  coat- 
ing admits  of  the  pipe  being  bent  without  flaking 
off,  which  would  quickly  permit  rust  and  conse- 
quent destruction   of  the  pipe,  the   zinc   coating 


Condulet  Type  YC  with  cov- 
er sealed,  showing  Plug 
Fuse  Cut-out. 


Type  J 
Norbitt  Conduletto  Recepta- 
cle with    Shade   Holder 
Groove. 


Type   YL 
With  Plug  Fuse  Cut-out. 


Condulet  Type  YD 
With  Plug  Fuse  Cut-out. 


Type  YS  with  Cartridge 
Fuse   Cut-out. 


PLATE  VI. 


92  WIRING    HOUSES 

being  preferable.  Rigid  conduit  is  installed  com- 
plete with  all  the  iron  boxes  to  contain  the 
switches,  receptacles  and  other  appliances,  before 
the  wire  is  drawn  in.  For  this  reason  it  admits- 
of  changes,  a  wire  being  easily  removed  or  re- 
placed without  in  any  way  disturbing  the  pipe. 
The  installing  of  iron  conduit  and  the  iron  boxes 
is  merely  a  mechanical  operation  involving  the 
cutting  and  threading  of  pipe  and  the  setting  of 
the  fittings.  The  conduit  itself  is  fastened  up  by 
pipe  straps.  Condulets,  as  they  are  generally 
termed,  are  metal  fittings  of  almost  every  con- 
ceivable kind  made  to  screw  on  the  pipe.  Ex- 
amples are  shown  in  the  illustration.  They  in- 
clude tees  with  porcelain  bushings  through  which 
the  wires  emerge,  elbows,  splice  boxes,  iron  switch 
boxes,  receptacle  boxes,  and  cutout  boxes.  Where 
sheet  iron  boxes  are  used,  the  threaded  conduit 
is  held  in  holes  in  them  by  locknuts  and  bushings.. 
In  the  condulets  locknuts  are  not  necessary  as 
threaded  lugs  or  nipples  form  part  of  the  box 
itself.  It  will  be  evident  that  wire  ends  coming 
out  of  the  end  of  an  iron  pipe  would  be  liable  to 
injury  on  the  sharp  edges.  To  prevent  this  in- 
jury the  pipe  is  reamed  out  and  bushings  with 
rounded  edges  used.  Sharp  edges  in  the  pipe  are 
always  to  be  avoided.  Even  when  two  pipes  are 
joined  together  with  couplings  the  pipes  are 
reamed  out  and  drawn  together  by  the  coupling. 
Wherever  possible,  the   switches,  receptacles  or 


CONDUIT  OR  PROTECTED    WIRING  93 

cutouts  are  installed  in  iron  boxes  forming  part 
of  the  pipe  system,  the  pipe  entering  these  boxes 
and  being  secured  thereto.  But  where  it  becomes 
necessary  to  lead  off  a  pair  of  wires  or  a  flexible 
cord  a  fitting  made  to  screw  on  the  pipe  is  neces- 
sary. 

A  system  of  iron  conduit,  just  like  the  armor 
of  a  flexible  armored  wire  or  BX  for  example, 
must  be  a  continuous  metallic  structure.  This  is 
to  insure  the  proper  grounding  of  the  system,  and 
is  insured  by  carefully  scraping  paint  or  rust  off 
all  threads  so  that  at  all  junctions  there  is  a  per- 
fect metal  to  metal  contact.  Bends  in  the  system 
are  obtained  in  two  ways,  by  bending  the  pipe  or 
by  using  fittings,  an  example  of  the  latter  being 
shown  in  the  full  page  illustration  of  a  switch 
and  ceiling  light  installation.  In  order  to  prevent 
strain  on  the  wire  when  being  pulled  in,  only 
1<>ur  cpiarter  bends  are  allowed  by  the  code  in  any 
one  run.  ^Yhere  more  bends  become  necessary, 
a  drawing  in  box  must  be  used  between  each  four 
bends  so  that  the  wire  has  only  this  maximum 
between  its  point  of  entry  and  where  the  pulling 
strain  is  applied. 

Concentric  Wiring.  A  system  of  wiring  much 
used  abroad  for  several  years  is  that  known  as 
concentric  wiring.  The  wire  itself  from  which 
the  name  is  derived  is  duplex,  the  conductors  be- 
ing made  up  together.  The  inner  wire  conductor 
is   insulated   in   the  regular  manner,   but   outside 


!l  1  WIRING    HOUSES 

of  this  insulation  a  spiral  or  tape  of  copper  or 
alloy  is  wrapped,  forming  the  second  conductor. 
This  outer  conductor  is  not  insulated  on  the 
outside  but  is  bare.  The  outer  conductor  is  how- 
ever thoroughly  grounded  and  therefore  there 
being  no  difference  of  potential  (Voltage)  be- 
tween this  bare  conductor  and  the  ground,  no 
danger  ensues. 

The  grounding  must  be  well  performed  and  a 
continuous  contact  must  be  assured  at  all  joints 
or  boxes.  These  contacts  are  not  made  with 
solder  but  with  clamp  sleeves. 

Special  fittings,  sockets,  switches,  etc.,  are  re- 
quired as  it  is  evident  that  the  mode  of  construc- 
tion of  the  two  conductors  would  not  admit  of 
the  ordinary  kind  being  used. 

The  General  Elecric  Company,  some  of  whose 
fittings  for  concentric  wiring  are  shown  here,  fur- 
nish a  bare  concentric  wire  with  the  outer  con- 
ductor or  sheath  of  tinned  sheet  copper,  folded 
longitudinally  around  the  inner  insulated  wire, 
with  a  full  lap.  This  tin  sheath  is  then  soldered 
where  it  laps,  making  it  continuous  electrically 
and  mechanically,  and  at  the  same  time  gas  tight 
and  water  tight. 

It  will  be  noted  on  referring  to  the  illustrations 
that  there  is  a  clamp  which  fits  over  and  makes 
the  contact  with  the  sheath,  and  a  screw  connector 
for  the  inner  wire.  This  is  most  clearly  shown  in 
the  view  of  the  back  of  the  receptacle. 


Concentric  Wire,  Outer  Conductor  Partly  Cut  and 
Bent  Out. 


Wheel   Bending   Tool. 


Xo.  171445 
Switch  and  Plug  Cut-out,  3  Wire  to  2  Wire. 


Xo.  171463 
Key  Receptacle. 


Xo.  171456. 
Sub-base  for  Receptacle. 


PLATE  VII. 


96  WIRING    HOUSES 

Owing  to  the  impracticability  of  making  taps 
or  splices  by  twisting  together  wires,  various 
fittings  have  been  designed  for  these  purposes. 

The  No.  171446  Junction  Box  for  example  is 
used  where  a  tap  or  a  switch  leg  is  to  be  taken 
off  a  circuit,  the  main  wire  passing  through  the 
center  of  the  block. 

The  Xo.  171448  inside  junction  box  is  used 
where  the  service  or  main  wire  runs  up  or  down 
in  the  angle  of  a  wall  which  in  this  form  of  wiring 
is  the  most  logical  place  for  a  riser.  This  box 
located  in  the  upper  angle  of  the  corner,  takes 
the  wire  from  above  op  below  and  distributes 
both  ways  along  the  walls  of  the  room. 

Switch  No.  171445  is  for  a  three  wire  service 
to  the  top  screws  in  ordinary  wire,  the  two  cir- 
cuits of  concentric  wire  joining  to  the  connecting 
clamp  on  each  side  of  the  lower  part  of  the  switch. 

A  ground  wire  is  run  from  the  middle  lower 
connection,  which  through  the  transverse  clamp, 
effectually  grounds  the  sheaths  of  both  the  right 
and  left  hand  circuits. 

The  wire  is  bent  to  fit  corners  with  a  special 
grooved  roller  tool  shown  in  the  illustration.  In 
the  method  of  installation  most  in  vogue  this  con- 
centric wire  is  merely  strapped  to  the  walls  or 
supports  with  metal  straps  and  screws. 

Where  the  wire  passes  through  the  floor  or 
partitions  it  is  protected  by  iron  pipe,  otherwise 
it  is  not  covered  in  any  wav. 


No.  171447. 

Four  Way   Branch 

Junction   Box. 


No.  171446. 

Three  Way  Branch 

Junction   Box. 


No.  171449 
Outside  corner 
Junction    Box. 


No.  171452 

Sub -base  for 
S.  P.  Snap  Switch. 


No.  171450. 

Snap  Switch 

Junction   Box. 


No.  171448. 
Inside  Corner 
Junction    Box. 


PLATE  VIII. 


98  WIRING    HOUSES 

It  will  be  seen  then  that  concentric  wiring  is 
simple.  Its  cost  of  construction  would  approxi- 
mate the  cheaper  kinds  of  open  work,  but  at 
greater  safety  and  speed  of  installation. 

The  safety  of  this  form  of  wiring  is  evident. 
Owing  to  the  perfect  ground  connection,  the  bare 
outer  wire  may  be  touched  with  impunity.  If 
the  ground  is  broken  at  any  point  the  current 
would  fail  as  the  continuity  of  the  circuit  would 
also  be  broken. 

Current  is  brought  to  the  meter  in  the  usual 
Avay,  the  concentric  wire  being  usually  installed 
for  the  actual  house  circuits  alone. 

Concentric  wiring  will  be  widely  introduced 
into  the  United  States  in  the  course  of  time. 

It  is  a  logical  and  well  tried  system  of  house 
wiring  for  inexpensive,  safe  installations,  and 
although  it  may  not  entirely  supplant  the  present 
cumbersome  methods,  it  will  find  a  wide  field  of 
application  in  the  electric  wiring  of  moderate 
sized  homes  and  business  places. 

For  some  time  to  come,  however,  the  immense 
investment  in  the  older  form  of  wires,  sockets, 
and  fittings  in  general,  and  the  tools  or  plant 
necessary  to  make  them,  will  necessitate  time  for 
readjustment  before  concentric  wiring  becomes 
general. 


Rigid  pipe  conduit  using 
condulets  to  make  bends. 


PLATE  IX. 


CHAPTER  VIII. 


The  National  Code. 

This  Code  comprises  over  200  pages  detailing 
how  electrical  wiring  should  be  done  to  be  safe. 
It  should  be  studied  and  followed  by  everyone 
doing  electrical  wiring. 

It  may  be  obtained  from  the  National  Board 
Headquarters  in  most  large  cities,  being  furnished 
free  to  interested  parties. 

The  following  extracts  will  assist  the  operator 
in  the  installation  of  inside  wiring  for  not  ex- 
ceeding 250  volts. 

Under  the  head  of  General  Suggestions  the 
Xational  Board  of  Fire  Underwriters  in  the 
National  Electrical  Code  make  the  following 
valuable  recommendations : 

"In  all  electrical  work,  conductors,  however  well  insu- 
lated, should  always  be  treated  as  bare,  to  the  end  that 
under  no  conditions,  existing  or  likely  to  exist,  can  a 
ground  or  short  circuit  occur,  and  so  that  all  leakage  from 
conductor  to  conductor,  or  between  conductor  and  ground, 
may  be  reduced  to  the  minimum. 

In  all  wiring  special  attention  should  be  paid  to  the  me- 
chanical execution  of  the  work.  Careful  and  neat  running, 
connecting,  soldering,  taping  of  conductors,  and  securing 
and  attaching  of  fittings,  are  specially  conducive  to  security 
and  efficiency,  and  are  strongly  advised. 

In  laying  out  an  installation,  except  for  constant  current 
systems,  every  reasonable  effort  should  be  made  to  secure 
distribution  centers  located  in  easily  accessible  places,  at 
which  points  the  cut-outs  and  switches  controlling  the 
several  branch  circuits  can  be  grouped  for  convenience 
and  safety  of  operation.  The  load  should  be  divided  as 
evenly  as  possible  among  the  branches,  and  all  complicated 
and  unnecessary  wiring  avoided. 

The  use  of  wire-ways    for   rendering  concealed   wiring 

100 


THE  NATIONAL  CODE  101 


permanently  accessible  is  most  heartily  endorsed  and  recom- 
mended;  and  this  method  of  accessible  concealed  con- 
struction is  advised  for  general  use." 

Class  C. 
INSIDE  WORK 

{Including  All  Work  for  Light,  Power  and  Heat  Protected 
by  Service  Cut-out  and  Switch.) 

General  Rules. 
16.     Wires. 

a.  Must  not  be  of  smaller  size  than  No.  14  B.  &  S.  gage, 

except  as  allowed  for  fixture  work  andi  pendant  cord. 

This  is  not  only  on  account  of  carrying  capacity,  but  also  for 
mechanical   strength. 

b.  Conductors  of  size  No.  8  B.  &  S.  gage  or  over  used 
in  connection  with  solid  knobs  must  be  securely  tied  there- 
to. If  wires  are  used  for  tying  they  must  have  an  insula- 
tion of  the  same  type  as  the  conductors  they  confine.  Solid 
knobs  or  strain  insulators  must  be  used  for  all  wires  at 
the  end  of  runs  where  conductors  are  terminated.  Split 
knobs  or  cleats  must  be  used  for  the  support  of  conductors 
smaller  than  No.  8  B.  &  S.  gage,  except  at  the  end  of  runs. 

Knobs  or  cleats  which  are  arranged  to  grip  the  wire, 
must  be  fastened  by  either  screws  or  nails.  If  nails  are 
used,  they  must  be  long  enough  to  penetrate  the  woodwork 
not  less  than  one-half  the  length  of  the  knob  and  fully  the 
thickness  of  the  cleat,  and  must  be  provided  with  washers 
which  will  prevent  under  reasonable  usage,  injury  to  the 
knobs  or  cleats. 

Leather  nail  heads  are  pieces  of  leather  on  nail  just  below 
bead  to  take  impact  of  hammer. 

Splice  should  be  open  to  allow  solder  to  penetrate.  See  a 
previous  page. 

c.  Must  be  so  spliced  or  joined  as  to  be  both  mechanically 
and  electrically  secure  without  solder.  The  joints  must 
then  be  soldered  unless  made  with  some  form  of  approved 
splicing  device,  and  covered  with  an  insulation  equal  to 
that  o?i  the  conductors. 

Stranded  wires  (except  in  flexible  cords)  must  be 
soldered  before  being  fastened  under  clamps  or  binding 
screws,  and  whether  stranded  or  solid,  when  they  have  a 
conductivity  greater  than  that  of  No.  8  B.  &  S.  gage  they 
must  be  soldered  into  lugs  for  all  terminal  connections, 
except  where  an  approved  solderless  terminal  connector 
is  used. 


102  WIRING    HOUSES 


d.  Must  be  separated  from  contact  with  walls,  floors, 
timbers  or  partitions  through  which  they  may  pass  by  non- 
combustible,  non-absorptive,  insulating  tubes,  such  as  glass 
or  porcelain,  except  at  outlets  where  approved  flexible 
tubing  is  required. 

Bushings  must  be  long  enough  to  bush  the  entire  length 
of  the  hole  in  one  continuous  piece,  or  else  the  hole  must 
first  be  bushed  by  a  continuous  waterproof  tube.  This 
tube  may  be  a  conductor,  such  as  iron  pipe,  but  in  that 
case  an  insulating  bushing  must  be  pushed  into  each  end 
of  it,  extending  far  enough  to  keep  the  wire  absolutely 
out  of  contact  with  the  pipe. 

c.  Where  not  enclosed  in  approved  conduit,  moulding 
or  armored  cable  and  where  liable  to  come  in  contact  with 
gas,  water,  or  other  metallic  piping  or  other  conducting 
material,  must  be  separated  therefrom  by  some  continuous 
and  firmly  fixed  non-conductor  creating  a  permanent  sep- 
aration. Must  not  come  nearer  than  two  (2)  inches  to 
any  other  electric  lighting,  power  or  signaling  wire,  not 
enclosed  as  above,  without  being  permanently  separated 
therefrom  by  some  continuous  and  firmly-fixed  non-con- 
ductor. The  non-conductor  used  as  a  separator  must  be 
in  addition  to  the  regular  insulation  on  the  wires.  Where 
tubes  are  used,  they  must  be  securely  fastened  at  the  ends 
to  prevent  them   from  moving  along  the  wire. 

Note. — This  applies  to  wires  not  in  conduit  or  armored  cable. 
Conduit  work  is  cheaper  in  the  long  run. 

Deviations  from  this  rule  may,  when  necessary,  be  al- 
lowed by  special  permission. 

/.  Must  be  so  placed  in  wet  places  that  an  air  space  will 
be  left  between  conductors  and  pipes  in  crossing,  and  the 
former  must  be  run  in  such  a  way  that  they  cannot  come 
in  contact  with  the  pipe  accidentally.  Wires  should  be 
run  over,  rather  than  under,  pipes  upon  which  moisture 
is  likely  to  gather  or  which,  by  leaking,  might  cause  trouble 
on  a  circuit. 

g.  The  installation  of  electrical  conductors  in  moulding, 
or  on  insulators,  in  elevator  shafts  will  not  be  approved, 
but  conductors  may  be  installed  in  such  shafts  if  encased 
in  approved  metal  conduits,  or  armored  cables. 

18.     Table  of  Allowable  Carrying  Capacities  of  Wires. 

</.  The  following  table,  showing  the  allowable  carryjng 
capacity  of  copper  wires  and  cables  of  ninety-eight  per 
cent   conductivity,    according   to   the    standard   adopted   by 


THE  NATIONAL  CODE  103 

18.     Allowable  Carrying  Capacities  of  Wires — continued. 

the   American   Institute   of    Electrical   Engineers,   must   be 
followed   in  placing  interior  conductors. 

For  insulated  aluminum  wire  the  safe  carrying  capacity 
is  eighty-four  per  cent  of  that  given  in  the  following  tables 
for  copper  wire  with  the  same  kind  of  insulation. 

Table  A  Table  B 

Rubber  Other 

Insulation  Insulations  Circular 

B.  &  S.  G.  Amperes  Amperes  Mils 

18 3 5 1,624 

16 6 10 2,583 

14 15 20 4,107 

12 20 25 6,530 

10 25 30 10,380 

8 35 50 16,510 

6 50 70 26,250 

5 55 80 33,100 

4 70 90 41,740 

3 80 100 52,630 

2 90 1:.':. 66,370 

1 100 150 83,690 

0 125 200 105,500 

00 150 225 133,100 

000 175 275 167,800 

0000 225 325 211,600 

Circular  Mils 

200,000 200 300 

300,000 275 400 

400,000 325 500 

500,000 400 600 

600,000 450 680 

700,000 500 760 

800,000 550 840 

900,000 600 920 

1,000,000 650 1,000 

1,100,000 690 1,080 

1 ,200,000 730 1 ,1  50 

1,  .100,000 770 1,220 

1,400,000 810 1,290 

1,500,000 850 1,360 

1,600,000 890 1 ,430 

1. 700,000 930 1,490 

i  ,800,000 970 l  ,:,:*) 

1,900,000 1,010 1,610 

2,000,000 1 ,050 1 .670 


KM  WIRING    HOUSES 


19.    Switches,   Cut-outs,   Circuit-Breakers,  Etc. 

a.  On  constant  potential  circuits,  all  service  switches  and 
all  switches  controlling  circuits  supplying  current  to  motors 
or  heating  devices,  and  all  fuses,  unless  otherwise  provided, 
must  be  so  arranged  that  the  fuses  will  protect  and  the 
opening  of  the  switch  will  disconnect  all  of  the  wires; 
that  is,  in  the  two-wire  system  the  two  wires,  and  the 
three-wire  system  the  three  wires,  must  be  protected  by 
the  fuses  and  disconnected  by  the  operation  of  the  switch. 

When  installed  without  other  automatic  overload  pro- 
tective devices  automatic  overload  circuit  breakers  must 
have  the  poles  and  trip  coils  so  arranged  as  to  afford 
complete  protection  against  overloads  and  short  circuits, 
and  if  also  used  in  place  of  the  switch  must  be  so  ar- 
ranged that  no  one  pole  can  be  opened  manually  without 
disconnecting  all  the  wires. 

b.  Must  not  be  placed  where  exposed  to  mechanical  in- 
jury nor  in  the  immediate  vicinity  of  easily  ignitible  stuff 
or  where  exposed  to  inflammable  gases  or  dust  or  to  fly- 
ings  of  combustible  material. 

Where  the  occupancy  of  a  building  is  such  that  switches, 
cut-outs,  etc.,  cannot  be  located  so  as  not  to  be  exposed 
as  above,  they  must  be  enclosed  in  approved  dust-proof 
cabinets  with  self-closing  doors,  except  oil  switches  and 
circuit   breakers  which   have   dust-tight   casings. 

c.  Must,  when  exposed  to  dampness,  either  be  enclosed 
in  a  moisture-proof  box  or  mounted  on  porcelain  knobs. 
The  cover  of  the  box  must  be  so  made  that  no  moisture 
which  may  collect  on  the  top  or  sides  of  the  box  can  enter 
it. 

23.     Automatic  Cut-outs. 

c.  Must  be  in  plain  sight,  or  enclosed  in  an  approved 
cabinet,  and  readily  accessible.  They  must  not  be  placed 
in  the  canopies  or  shells  of  fixtures. 

Link  fuses  may  be  used  only  when  mounted  on  approved 
bases  and  must  be  enclosed  in  dust-tight,  fire-proofed 
cabinets,   except  on  switchboards. 

d.  Must  be  so  placed  that  no  set  of incandes- 
cent lamps,  whether  grouped  on  one  fixture  or  on  several 
fixtures  or  pendants  (nor  more  than  16  sockets  or  recep- 
tacles) requiring  more  than  660  watts,  will  be  dependent 
upon  one  cut-out. 

There  are  exceptions  allowed  individually  for  particular  cases. 


THE  NATIONAL  CODE  105 

e.  The  rated  capacity  of  fuses  must  not  exceed  the  allow- 
able carrying  capacity  of  the  wire  as  given  in  No.  18 

The  idea  of  a  fuse  is  primarily  to  protect  the  wiring  wherein 
the  greatest  fire  danger  exists. 

Fixture  wire  or  flexible  cord  of  No.  18  B.  &  S.  gage, 
will  be  considered  as  properly  protected  by  10  ampere  fuses. 

This  is  a  miximum  and  does  not  mean  that  a  lower  fuse  may 
not    be   used. 

For  circuits  having  a  maximum  capacity  greater  than 
that  for  which  enclosed  fuses  are  approved  circuit  breakers 
alone  will  be  approved. 

26.     Wires. 

General  Rules. 

a.  Where  entering  cabinets  must  be  protected  by  ap- 
proved bushings,  which  fit  tightly  the  holes  in  the  box 
and  are  well  secured  in  place.  The  wires  should  com- 
pletely fill  the  holes  in  the  bushings  so  as  to  keep  out  the 
dust,  tape  being  used  to  build  up  the  wires  if  necessary. 
On  concealed  knob  and  tube  work  approved  flexible  tub- 
ing will  be  accepted  in  lieu  of  bushings,  provided  it  shall 
extend  from  the  last  porcelain  support  into  the  cabinet. 

b.  Must  not  be  laid  in  plaster,  cement  or  similar  finish, 
and  must  never  be  fastened  with  staples. 

c.  Must  not  be  fished — pulled  dozmi  in  walls  or  under 
flooring — fbr  any  great  distance,  and  only  in  places  where 
the  inspector  can  satisfy  himself  that  the  rules  have  been 
complied  with. 

d.  Twin  wires  must  never  be  used,  except  in  conduits, 
or  where  flexible  conductors  are  necessary. 

e.  Must,  where  exposed  to  mechanical  injury,  be  suitably 
protected.  When  crossing  floor  timbers  in  cellars,  or  in 
rooms  where  they  might  be  exposed  to  injury,  wires  must 
be  installed  in  approved  conduit  or  armored  cable  or  be 
attached  by  their  insulating  supports  to  the  under  side  of 
a  wooden  strip,  not  less  than  one-half  inch  in  thickness, 
and  not  less  than  three  inches  in  width.  Instead  of  the 
running  boards,  guard  strips  on  each  side  of  and  close 
to  the  wires  will  be  accepted.  These  strips  to  be  not  less 
than  seven-eighths  of  an  inch  in  thickness  and  at  least 
as  high  as  the  insulators. 

Protection  on  side  walls  must  extend  not  less  than  seven 
feet  from  the  floor  and  must  consist  of  substantial  boxing, 
retaining  an  air  space  of  one  inch  around  the  conductors. 


106  WIRING    HOUSES 

closed  at  the  top  (the  wires  passing  through  bushed  holes) 
or  approved  metal  conduit  pipe  of  equivalent  strength. 

When  metal  conduit  or  pipe  is  used,  the  insulation  of 
each  wire  must  be  reinforced  by  approved  flexible  tubing 
extending  from  the  insulator  next  below  the  pipe  to  the 
one  next  above  it. 

This  acts  as  a  non-shiftable  extra  insulation  through  the  metal 
pipe. 

The  two  or  more  wires  of  a  circuit  each  with  its  flexible 
tubing  (when  required),  if  carrying  alternating  current 
must,  or  if  direct  current,  may  be  placed  within  the  same 
pipe. 

Here  the  flexible  tubing  is  merely  extra  insulation.  In  all  cases 
it  is  preferable  to  put  both  wires  of  a  circuit  in  the  same  metal 
conduit.  It  must  be  done  when  alternating  current  is  used  on 
account  of  the  danger  of  the  iron  pipes  heating  if  two  were  used. 
This  refers  to  metal  conduit  only. 

In  damp  places  the  wooden  boxing  may  be  preferable 
because  of  the  precautions  which  would  be  necessary  to 
secure  proper  insulation  if  the  pipe  were  used.  With  this 
exception,  however,  iron  piping  is  considered  preferable 
to  the  wooden  boxing,  and  its  use  is  strongly  urged.  It 
is  especially  suitable  for  the  protection  of  wires  near  belts, 
pulleys,  etc. 

/.  When  run  in  unfinished  attics,  or  roof  spaces,  will  be 
considered  as  concealed,  and  when  run  in  close  proximity 
to  water  tanks  or  pipes,  will  be  considered  as  exposed  to 
moisture. 

In  unfinished  attics,  or  roof  spaces,  wires  are  considered 
as  exposed  to  mechanical  injury,  and  must  not  be  run  on 
knobs  on  upper  edge  of  joints. 

Special  Rules. 
For  Open  Work. 

In  dry  places. 

g.  Must  have  an  approved  rubber  slow-burning  weather- 
proof, or  slow-burning  insulation. 

h.  Must  be  rigidly  supported  in  non-combustible,  non- 
absorptive  insulators,  which  will  separate  the  wires  from 
each  other  and  from  the  surface  wired  over  in  accordance 
with  the  following  table : 


THE   NATIONAL  CODE  107 


Distance  from  Distance  between 

Voltage.  Surface.  Wires. 

0   to   300  y2    inch  2l/2    inch 

301   to   550  1    inch  4   inch 

Rigid  supporting  requires  under  ordinary  conditions, 
where  wiring  along  fiat  surfaces,  supports  at  least  every 
four  and  one-half  feet.  If  the  wires  are  liable  to  be  dis- 
turbed, the  distance  between  supports  must  be  shortened 
In  buildings  of  mill  construction,  mains  of  not  less  than 
No.  8  B.  &  S.  gage,  where  not  liable  to  be  disturbed,  may 
be  separated  about  six  inches,  and  run  from  timber  to 
timber,  not  breaking  around,  and  may  be  supported  at 
each  timber  only. 

Must  not  be  "dead-ended"  at  a  rosette,  socket  or  re- 
ceptacle unless  the  last  support  is  within  twelve  inches  of 
the  same. 

For  Moulding  Work  (Wooden  and  Metal). 

Note. — Wooden  moulding  is  practically  obsolete  and  not  al- 
lowed in  most  places. 

Metal  mouldings  must  not  be  used  for  circuits  requiring 
more  than   1,320   watts   of  energy. 

For  Conduit  Work. 

n.  Must  have  an  approved  rubber  insulating  covering 
(Type  Letter  R.  D.),  and  must  within  the  conduit  tubing 
be  without  splices  or  taps. 

o.  Must  not  be  drawn  in  until  all  mechanical  work  on 
the  building  has  been,  as  far  as  possible,  completed. 

Conductors  in  vertical  conduit  risers  must  be  supported 
within  the  conduit  system  in  accordance  with  the  follow- 
ing table : 

Xo.  14  to  0  every  100  feet. 
Xo.  00  to  0000  every  80   feet. 
0000  to  350,000  C.  M.  every  60  feet. 
350,000  C  M.  to  500,000  C.  M.  every  50  feet. 
.•.0(1,000  C.  M.  to  750,000  C.  M.  every  40  feet. 
750,000  C.  M.  every  35  feet. 

For  Concealed  "Knob  and  Tube"  Work. 

q.   Must   have    an    approved    rubber    insulating    covering. 

r.  Must  be  rigidly  supported  on  non-combustible,  non- 
absorptive  insulators  which  separate  the  wire  at  least  one 
inch    from  the   surface   wired    over.      Should  preferably  be 


108  WIRING    HOUSES 


run  singly  on  separate  timbers,  or  studding,  and  must  be 
kept  at  least  five  inches  apart. 

Must  be  separated  from  contact  with  the  walls,  floor 
timbers  and  partitions  through  which  they  may  pass  by 
non-combustible,  non-absorptive,  insulating  tubes,  such  as 
glass  or  porcelain.  Wires  passing  through  cross  timbers 
in  plastered  partitions  must  be  protected  by  an  additional 
tube  extending  at  least  four  inches  above  the  timber. 

Rigid  supporting  requires,  under  ordinary  conditions, 
where  wiring  along  flat  surfaces,  supports  at  least  every 
four  and  one-half  feet.  If  the  wires  are  liable  to  be  dis- 
turbed the  distance  between  supports  must  be  shortened. 

At  distributing  centers,  outlets  or  switches  where  space 
is  limited  and  the  five-inch  separation  cannot  be  maintained, 
each  wire  must  be  separately  encased  in  a  continuous  length 
of  approved  flexible  tubing. 

s.  When  in  a  concealed  knob  and  tube  system,  it  is  im- 
practicable to  place  the  whole  of  a  circuit  on  non-com- 
bustible supports  of  glass  or  porcelain,  that  portion  of  the 
circuit  which  cannot  be  so  supported  must  be  installed 
with  approved  metal  conduit,  or  approved  armored  cable, 
except  that  if  the  difference  of  potential  between  the  wires 
is  not  over  300  volts,  and  if  the  wires  are  not  exposed  to 
moisture,  they  may  be  fished  if  separately  encased  in  ap- 
proved flexible  tubing,  extending  in  continuous  legths  from 
porcelain  support  to  porcelain  support,  from  porcelain  sup- 
port to  outlet,  or  from  outlet  to  outlet. 

t. .When  using  either  conduit  or  armored  cable  in  mixed 
concealed  knob  and  tube  work,  the  requirements  for  con- 
duit work  or  armored  cable  work  must  be  complied  with 
as  the  case  may  be. 

u.  Must  at  all  outlets,  except  where  conduit  is  used, 
be  protected  by  approved  flexible  tubing,  extending  in  con- 
tinuous lengths  from  the  last  porcelain  support  to  at  least 
one  inch  beyond  the  outlet 

When  the  surface  at  any  outlet  is  broken,  it  must  be 
repaired  so  as  to  leave  no  holes  or  open  spaces  at  such 
outlet. 

For  Fixture  Work. 

v.  Must  be  not  smaller  than  No.  18  B.  &  S.  gage,  and 
must  have  an  approved  rubber  insulating  covering. 


THE  NATIONAL  CODE  109 


27.     Armored  Cables. 

a.  Must  be  continuous  from  outlet  to  outlet  or  to  junc- 
tion boxes  or  cabinets,  and  the  armor  of  the  cable  must 
properly  enter  and  be  secured  to  all  fittings,  and  the  entire 
system  must  be  mechanically  secured  in  position. 

In  case  of  service  connections  and  main  runs,  this  in- 
volves running  such  armored  cable  continuously  into  a 
main  cut-out  cabinet  or  gutter  surrounding  the  panel  board, 
as  the  case  may  be. 

b.  Must  be  equipped  at  every  outlet  with  an  approved 
outlet  box  or  plate,  as  required  in  conduit  work. 

For  concealed  work  in  walls  and  ceilings  composed  of 
plaster  on  wooden  joist  or  stud  construction,  outlet  boxes 
or  plates  and  also  cut-out  cabinets  must  be  so  installed 
that  the  front  edge  will  not  be  more  than  one-fourth  inch 
back  of  the  finished  surface  of  the  plaster,  and  if  this 
surface  is  broken  or  incomplete  it  shall  be  repaired  so  that 
it  will  not  show  any  gaps  or  open  spaces  around  the  edges 
of  the  outlet  box  or  plate  or  of  the  cut-out  cabinet.  On 
wooden  walls  or  ceilings,  outlet  boxes  or  plates  and  cut- 
out cabinets  must  be  so  installed  that  the  front  edge  will 
either  be  flush  with  the  finished  surface  or  project  there- 
from. This  will  not  apply  to  concealed  work  in  walls  or 
ceilings  composed  of  concrete,  tile  or  other  non-combustible 
material. 

In  buildings  already  constructed  where  the  conditions- 
are  such  that  neither  outlet  box  nor  plate  can  be  installed, 
these  appliances  may  be  omitted  by  special  permission,  pro- 
vided the  armored  cable  is  firmly  and  rigidly  secured  in 
place. 

c.  Must  have  the  metal  armor  of  cables  permanently 
and  effectually  grounded  to  water  piping,  gas  piping  or 
other  suitable  grounds,  provided  that  when  connections 
are  made  to  gas  piping,  they  must  be  on  the  street  side  of 
the  meter.  Tf  the  armored  cable  system  consists  of  several 
separate  sections,  the  sections  must  be  bonded  to  each 
ether,  and  the  system  grounded,  or  each  section  may  be 
separately  grounded,  as  required  above. 

The  armor  of  cables  and  gas  pipes  must  be  securely 
fastened  in  outlet  boxes,  junction  boxes  and  cabinets,  so 
as  to  secure  good  electrical  connection. 

The    clamp    connectors  illustrated   elsewhere  take   care    of  this. 


110  WIRING    HOUSES 


27.     Armored  Cables — continued. 

If  armor  of  cables  and  metal  of  couplings,  outlet  boxes, 
junction  boxes,  cabinets  or  fittings  baving  protective  coat- 
ing of  non-conducting  material,  such  as  enamel  are  used, 
such  coating  must  be  thoroughly  removed  from  threads 
of  both  couplings  and  the  armor  of  cables,  and  from 
surfaces  of  the  boxes,  cabinets  and  fittings  where  the 
armor  of  cables  or  ground  clamp  is  secured  in  order  to 
obtain  the  requisite  good  connection.  Grounded  pipes  must 
be  cleaned  of  rust,  scale,  etc.,  at  place  of  attachment  of 
ground  clamp. 

Connections  to  grounded  pipes  and  to  armor  of  cables 
must  be  exposed  to  view  or  readily  accessible,  and  must 
be   made  by  means  of  approved  ground  clamps. 

Ground  wires  must  be  of  copper,  at  least  No.  10  B.  &  S. 
gage  (where  largest  wire  contained  in  cable  is  not  greater 
than  No.  0  B.  &  S.  gage),  and  need  not  be  greater  than 
No.  4  B.  &  S.  gage  (where  largest  wire  contained  in  cable 
is  greater  than  No.  0  B.  &  S.  gage).  They  shall  be  pro- 
tected from  mechanical  injury. 

The  ground  for  the  armored  cable  system  is  not  to  be 
considered  as  a  ground  for  a  secondary  system. 

d.  When  installed  in  so-called  fireproof  buildings  in 
•course  of  construction  or  afterwards  if  exposed  to  mois- 
ture, or  where  it  is  exposed  to  the  weather,  or  in  damp 
places,  such  as  breweries,  stables,  etc.,  the  cable  must  have 
a  lead  covering  placed  between  the  outer  braid  of  the  con- 
ductors and  the  steel  armor. 

The  lead  covering  is  not  to  be  required  when  the  cable 
is  run  against  brick  walls  or  laid  in  ordinary  plaster  walls 
unless  same  are  continuously  damp. 

e.  Where  entering  junction  boxes,  and  at  all  other  out- 
lets, etc.,  must  be  provided  with  approved  terminal  fittings 
which  will  protect  the  insulation  of  the  conductors  from 
abrasion,  unless  such  junction  or  outlet  boxes  are  specially 
designed  and  approved  for  use  with  the  cable. 

/.  Junction  boxes  must  always  be  installed  in  such  a 
manner  as  to  be  accessible. 

g.  For  alternating  current  systems  must  have  the  two 
or  more  conductors  of  the  circuit  enclosed  in  one  metal 
armor. 

h.  All  bends  must  be  so  made  that  the  armor  of  the 
cable  will  not  be  injured.  The  radius  of  the  curve  of  the 
inner  edge  of  any  bend  not  to  be  less  than  iy2  inches. 


THE  NATIONAL  CODE  111 


28.     Interior   Conduits. 

a.  No  conduit  smaller  than  one-half  inch  electrical  trade 
size  shall  be  used. 

_  b.  Must  be  continuous  from  outlet  to  outlet  or  to  junc- 
tion boxes  or  cabinets,  and  the  conduit  must  properly 
enter,  and  be  secured  to  all  fittings  and  the  entire  system 
must  be  mechanically  secured  in  position. 

In  case  of  service  connections,  and  main  runs,  this  in- 
volves running  each  conduit  continuously  into  a  main  cut- 
out cabinet  or  gutter  surrounding  the  panel  board,  as  the 
case  may  be. 

Departure  from  this  rule  may  be  authorized  in  case  of 
underground  services  by  special  permission. 

c.  Must  be  first  installed  as  a  complete  conduit  system, 
without  the  conductors. 

d.  Must  be  equipped  at  every  outlet  with  an  approved 
outlet  box  or  plate.  At  exposed  ends  of  conduit  (but  not 
at  fixture  outlets)  where  wires  pass  from  the  conduit  sys- 
tem without  splice,  joint  or  tap,  an  approved  fitting  having 
separately  bushed  holes  for  each  conductor  must  be  used. 
Departure  from  this  rule  may  be  authorized  by  special 
permission. 

Outlet  plates  must  not  be  used  where  it  is  practicable 
to  install  outlet  boxes.     .     .     . 

In  buildings  already  constructed  where  the  conditions 
are  such  that  neither  outlet  box  nor  plate  can  be  installed, 
these  appliances  may  be  omitted,  providing  the  conduit 
ends  are  bushed  and  secured. 

It  is  suggested  that  outlet  boxes  and  fittings  having  con- 
ductive coatings  be  used  in  order  to  secure  better  electrical 
contact  at  all  points  throughout  the  conduit  system. 

This  refers  to  the  zinc  coated  conduit  as  being  better  than 
enameled  conduit. 

e.  Metal  conduits  where  they  enter  junction  boxes,  and 
at  all  other  outlets,  etc.,  must  be  provided  with  approved 
bushings  or  fastening  plates  fitted  so  as  to  protect  wire 
from  abrasion,  except  when  such  protection  is  obtained  by 
the  use  of  approved  nipples,  properly  fitted  in  boxes  or 
devices. 

/.  Must  have  the  metal  of  the  conduit  permanently  and 
effectually  grounded  to  water   piping,  gas  piping  or  other 
suitable  grounds,  provided  that  when  connections  arc  made 


112  WIRING    HOUSES 


28.    Interior  Conduits — continued. 

to  gas  piping,  they  must  be  on  the  street  side  of  the  meter. 
If  the  conduit  system  consists  of  several  separate  sections, 
the  sections  must  be  bonded  to  each  other,  and  the 
system  'grounded,  or  each  section  may  be  separately 
grounded,  as  required  above.  Where  short  sections  of 
conduit  (or  pipe  of  equivalent  strength)  are  used  for  the 
protection  of  exposed  wiring  on  side  walls,  and  such  con- 
duit or  pipe  and  wiring  is  installed  as  required  by  No, 
26  c,  the  conduit  or  pipe  need  not  be  grounded. 

Conduits  and  gas  pipes  must  be  securely  fastened  in 
outlet  boxes,  junction  boxes  and  cabinets,  so  as  to  secure 
good  electrical  connections. 

Taken  care  of  by  lock  nuts  and  bushings  or  by  condulets 
where  the  pipe  is  held  by  a  threaded  nipple. 

If  conduit,  couplings,  outlet  boxes,  junction  boxes,  cabi- 
nets or  fittings,  having  protective  coating  ot  non-conduct- 
ing material  such  as  enamel  are  used,  such  coating  must 
be  thoroughly  removed  from  threads  of  both  couplings  and 
conduit,  and  such  surfaces  of  boxes,  cabinets  and  fittings 
where  the  conduit  or  ground  clamp  is  secured  in  order  to 
obtain  the  requisite  good  connection.  Grounded  pipes 
must  be  cleaned  of  rust,  scale,  etc.,  at  place  of  attachment 
of  ground  clamp. 

Connections  to  grounded  pipes  and  to  conduit  must  be 
exposed  to  view  or  readily  accessible,  and  must  be  made 
by  means  of  approved  ground  clamps 

Ground  wires  must  be  of  copper,  at  least  No.  10  B.  &  S. 
gage  (where  largest  wire  contained  in  conduit  is  not  greater 
than  No.  0  B.  &  S.  gage),  and  need  not  be  greater  than 
No.  4  B.  &  S.  gage  (where  largest  wire  contained  in  con- 
duit is  greater  than  No.  0  B.  &  S.  gage).  They  shall  be 
protected  from  mechanical  injury. 

The  ground  on  the  conduit  system  is  not  to  be  considered 
as  a  g'/ound  for  a  secondary  system  (see  No.  15). 

g.  Junction  boxes  must  always  be  installed  in  such  a 
manner  as  to  be  accessible. 

h.  All  elbows  or  bends  must  be  so  made  that  the  con- 
duit will  not  be  injured.  The  radius  of  the  curve  of  the 
inner  edge  of  any  elbow  not  to  be  less  than  three  and 
one-half  inches.  Must  have  not  more  than  the  equivalent 
of  four  quarter  bends  from  outlet  to  outlet,  the  bends  at 
the  outlets  not  being  counted. 


UC  SOUTHERN  REGIONAL  LIBRARY  FACILITY 


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